I went to install Rapid SVN from the Ubuntu Software Center today as I have done before - it wasn't there.  I can install this using the command:  sudo apt-get install rapidsvn  Why can I apt-get install rapidsvn but not see it within the Ubuntu Software Center GUI?

I tried to enable additional repositories according to the instructions from , however my Ubuntu Software app is still missing a lot of popular apps. Is there anything I'm missing?  Ubuntu 16.10 Ubuntu Software app 3.20.1


I was watching a video by Blender Guru and noticed that corners in his scene have shadows in the Solid View. However, my corners do not have shadows like he does. Is this an setting I can turn on in Blender? If so, how can I turn it on?

Sample frame:   Until EEVEE gets into an official version, I'm trying different settings to test a character animation I made in cycles. Just good enough to see the character and floor shadows. No need for it to be super sharp it's just a test. I need the floor to see how the feet land. Her eyes have no lens so there is no transparencies to worry about.  1920x1080 resize @ 50% if lower difficult to see any details.  Multiple importance off.  There is only the floor and the character with a gray background as a light source.  Renders = 7 samples.  GPU rendering with my GTX1060 3GB Tiles are maxed for GPU performance @480X270 = exactly 4 tiles per frame. I got 0.99 frames per second.   CPU i7 2600K Tiles are maxed for CPU performance @48X27 = exactly 40 tiles per frame. I got 0.94 frames per second.  What else could I check or uncheck to speed that up even more?


I have managed to work out the answer in some dirty brute force manner and was wondering if there was an easier way.  The question is, find the locus of points of $z$ such that:  $$ (z-2+i)^2+(z-2-i)^2+2zz^*+6=0$$  I substituted $z=x+iy$ and just worked out a relation and got a parabola.  Is there an easier way?  Thank you

I am tasked to sketch the locus of complex numbers $z$ that satisfies $$(z-2+i)^2 + (z^*-2-i)^2 + 2zz^* + 6 = 0$$ I was wondering if there’s a special trick to this question, or if this is only solvable by plugging in $z=x+iy$ ? I noticed that the second term is the conjugate of the first, and wanted to substitute $w = z-2+i$, however this gives me a complicated expression for $zz^*$ which makes it more confusing. Is there a trick I’m missing out? Thanks! Edit: I have already solved it through direct substitution (parabola intersecting real axis at $x=3$ and $x=-1$) but it took a good 5 minutes or so, expanding everything correctly, which seems rather long (I was attempting it under exam conditions). I was just wondering if it is possible to exploit the $w$ substitution I made in particular.


I have     @RequestMapping(value ="/getTaxiByPhone",method = RequestMethod.GET) public @ResponseBody String getTaxiByPhone(@RequestParam ("phone") String phone){     int count=0;     for (int i=0; i<taxiList.size();i++){         if ((taxiList.get(i).getPhone()).equals(phone)){             count++;         }     }     return "found "+count; } @RequestMapping(value ="/getTaxiPhone",method = RequestMethod.GET) public @ResponseBody String getAllTaxi(@RequestParam ("id") int id){     return taxiList.get(id).getPhone(); }  @RequestMapping(value ="/getAllTaxi",method = RequestMethod.GET) public @ResponseBody List<Taxi> getAllTaxi(){     return taxiList; }   For example getTaxi?id=2 returned {"taxi_city_id":[55000001,67000001],"taxi_id":1113,"taxi_name":"zxcv","taxi_phone":"+73812999997"} , but if you try getTaxiByPhone?phone=+73812999997 you will not find any objects, because if you try return phone parameter with count (return "found "+count+" for phone"+ phone;), you will see found 0 for phone 73812999997. This means that sign '+' lost when spring parse url.

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


Forgive me, I'm a late bloomer with regards to the Stargate TV series (loved Universe when originally shown, but never watched SG1 or Atlantis, until now, thanks to streaming services have begun binge watching) Was always a fan of the original Stargate movie. That background aside...   In Atlantis a puddle jumper gets stuck in a gate and it is said that nothing rematerializes at the other end until the entire object passes completely into the event horizon from the origin side. Yet a continuous beam is able to be fired through a stargate to attack the Atlantis' shields and must still be passing into the stargate while the front is emerging from the destination end.   How is this possible? does this not contradict the previous episodes? I know you could argue that the beam is made up of discrete packets of particles (pulses perhaps) but if that were the explanation then there would be no reason why the windscreen of the puddle jumper and the front crew couldn't rematerialize as they themselves were "discrete packets" compared to the puddle jumper's hull.   Is there an explanation in the series that I've missed or is this a plot loophole?

We know that Stargates only reintegrate matter at the destination once the entire object has gone through the gate on the departing side.  This behavior is made explicit in the Atlantis episode 38 minutes (Season 1, Episode 4).  The episode makes clear that a whole person is not a discrete object to be reintegrated, but rather the entire system that person is a part of.  (In 38 minutes half of a puddle jumper enters the gate, but then gets stuck so two crew members and half the jumper have dematerialized, while the several other Atlantis members and the back half of the jumper remain outside the gate.  The crux of the episode is that if the back half of the jumper does not enter the gate, then the front half + 2 crew members will never rematerialize.)  However, this behavior does not seem to apply to gates in the Milky Way.  A few notable times this behavior did not apply and partial objects got rematerialized:   Ernest Little field in the episode Torment of Tantalus from Season 1.  We can clearly see in the archive footage that Ernest is attached to a breathing apparatus on the Earth side of the gate (as he is in some sort of diving suit) and that the breathing tube and apparatus remain on the earth side (there is close up footage of the severed breathing tubes in the archive Daniel is watching).  So, how could he have reintegrated at Heliopolis?  Should not the gate have been waiting for the rest of the breathing apparatus to come through? In episode two (“The Enemy Within”), when Kawalsky is taken over by a Goa'uld symbiote, O'Neill kills him holding his head half-way in the gate and calling for it to be closed, thus cutting off half of Kawalsky’s head. Teal'c, in his efforts to recover O'Neill from Edora in "A Hundred Days," shoots a projectile attached to a rope through the gate.  The gate on Edora is buried, and the projectile lodges itself in the rock on the other side, allowing Teal'c to climb up the rope on the Earth side, through the gate, and be suspended above the event horizon on the Edora side.  How can the projectile and rope rematerialize on the Edora side while some part of the rope is still on the Earth side (so that Teal'c may climb it)? In 200 the puppets manage to rematerialize without their puppet strings going through the gate!   Is this a difference in behavior between Milky Way gates and Pegasus gates or is something else going on here?  Does the gate technology make some sort of distinction between ropes and non-ropes?  (It is not between animate and inanimate objects as a partial puddle jumper is unable to rematerialize.)


I have a question regarding ArcMap. Lets say I have a .shp with watersheds and a .shp with drainage lines. How can I combine both, so that I can display single watersheds and the length of their inner streams. Just like in the nice picture below.    I want to access the length of the stream segments inside each catchment. I have tried several clipping methods but have still no useful results.  Thanks for the help!

I'm working with two data sets:   NHD polyline stream layer for my entire state HUC Watershed boundary Polygons for the entire state   I am looking for a way to calculate the total length of streams within each watershed boundary polygon, and would ideally like to have each polygon then attributed with the sum of stream miles within its boundary.  Can anyone help me?


I have an Array of Room objects from the Room class that has a toString method. I want to take the Room[] and convert it to String[] using the toString method of each room object in the list. I get a null pointer exception when running. Here a snip of my code (the method eclipse states is throwing the error).  public String[] getDescriptions() {      String[] descriptionList = new String[5];     int boardNumber = 0;     for (Room current : this.board) {         descriptionList[boardNumber] = current.toString();         boardNumber++;     }     return descriptionList; }   Thank you in advance.

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I am  analyzing the data of a cohort study. there are three sets of paired data (same measures on same subjects in 3 different point of time).  The problem is that the third set of data have more than 50% missing values.  My question is that, how can I deal with these missing values? does MI help in these repeated measures? it seems that if I delete the missing I loose more than half of my data set.

I have a data set for a predictive model(predicting survival rate with certain acute medical condition on some animals) with 25 predictors where around 30% of the predictors are complete, 3 predictors are sitting at 30%,25% and 20% missing, and the others are missing at around 5% level. Around 50% of my data are complete cases. I'm new to dealing with missing values so I have a couple of questions regarding how to deal with it:   What can I do with the variable with 30% missing assuming it's MAR? Is 30% too high for imputation? What kinds of metrics can I use to make the decision between removal of the predictor, listwise removal, imputation or some other options? How should I deal with a predictor with 20% - 25% missing when I have reason to believe that it's MNAR? I'm thinking of using imputation on the remaining predictors with around 5% missingness. How do I make the decision on which imputation methods to use? Are they chosen on a case by case basis based on the individual predictors? How does one impute categorical values?  How does(should?) the imputation carry out in practice? Should it use complete cases or compute it iteratively somehow?  Does feature selection comes in before or after dealing with missing values? if at all?


My question is similar but opposite to to   For me, telnet to the local port works but trying with IP does not work :(  I am running pgbouncer on port 6432:  $ telnet 192.x.x.x 6432 Trying 192.x.x.x... telnet: Unable to connect to remote host: Connection refused   I set listen_addr = *, but still using telnet with IP from another server is not working.  See  for the same scenario (but no useful answer).  The output of netstat -plnt is   tcp 0 0 127.0.0.1:6432 0.0.0.0:* LISTEN 19879/./pgbouncer   How can I fix this?

My application listens on port 8180.  When I am trying to connect to port 8180 locally. Connection got refused. But when I am trying to connect to port with ip . I am able to connect.  [root@MUMLGOMAPP002 ~]# telnet 10.209.129.54 8180 Trying 10.209.129.54... Connected to MUMLGOMAPP002 (10.209.129.54). Escape character is '^]'. ^] telnet> q Connection closed.   [root@MUMLGOMAPP002 ~]# telnet localhost 8180 Trying 127.0.0.1... telnet: connect to address 127.0.0.1: Connection refused telnet: Unable to connect to remote host: Connection refused   My interface is :  [root@MUMLGOMAPP002 ~]# ifconfig bond0     Link encap:Ethernet  HWaddr 44:1E:A1:73:F7:50           inet addr:10.209.129.54  Bcast:10.209.129.63  Mask:255.255.255.224           UP BROADCAST RUNNING MASTER MULTICAST  MTU:1500  Metric:1           RX packets:322997568 errors:23 dropped:0 overruns:0 frame:0           TX packets:304470664 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:0           RX bytes:213628580915 (198.9 GiB)  TX bytes:217449664400 (202.5 GiB)   I would like to know what is the difference between telnetting localhost and ip.


I am traveling from Toronto to Ahmedabad via Chicago and Doha and same way back. I am traveling from Toronto to Chicago in Air Canada and in Qatar from Chicago to Doha to Ahmedabad. Same way back. How will the baggage claim, customs and immigration work? While coming back, do I have to get my luggage at Chicago airport, undergo customs, and take all the baggage with me on the train, change terminals, and re-check my luggage at the Air Canada counter, or do I not have to worry about my luggage and it gets automatically transferred?

I am flying from Doha to Philadelphia by Qatar Airway. While in Philadelphia, I need to change flight to US Airway. But I only have 1 hour and a half before my next flight to Birmingham. Do I have enough time to check out and check in my baggage?  1.Kuala Lumpur (KUL)  Tue, 21 Jul 2015 20:50  2.Doha (DOH)  Tue, 21 Jul 2015 23:20  3.Doha (DOH)  Wed, 22 Jul 2015 01:10   Philadelphia (PHL)  Wed, 22 Jul 2015 07:45   5.Philadelphia (PHL)  Wed, 22 Jul 2015 09:40 Terminal F  6.Birmingham (BHM)  Wed, 22 Jul 2015 11:00


I'm trying to implement Collection interface for study purpose. My add() and toArray() method looks like:  public class ArrayCollection<T> implements Collection<T> {  private T[] m = (T[])new Object[10];  private int size = 0;  @Override public boolean add(final T t) {             m[size++] = t;     return true; }  @Override public Object[] toArray() {     T[] array = (T[]) new Object[size()];     int i = 0;     for (T item : ArrayCollection.this) {         array[i++] = item;     }     return array; }   But when I perform testing:  @Test public void testToArray() throws Exception {     final Collection<Integer> testInstance = new ArrayCollection<>();     testInstance.add(1);     testInstance.add(2);     testInstance.add(3);      final Integer[] result = testInstance.toArray();      assertEquals((Integer)1, result[0]);     assertEquals((Integer)2, result[1]);     assertEquals((Integer)3, result[2]);     assertEquals(3, result.length); }   I get error:   ArrayCollectionTest.java:32: error: incompatible types: Object[] cannot be converted to Integer[] final Integer[] result = testInstance.toArray();   I completelly don't uderstand how to fix this problem and what I'm doing wrong.

I think there must be something subtle going on here that I don't know about. Consider the following:  public class Foo<T> {   private T[] a = (T[]) new Object[5];    public Foo() {     // Add some elements to a   }    public T[] getA() {     return a;   } }   Suppose that your main method contains the following:  Foo<Double> f = new Foo<Double>(); Double[] d = f.getA();   You will get a CastClassException with the message java.lang.Object cannot be cast to java.lang.Double.  Can anyone tell me why? My understanding of ClassCastException is that it is thrown when you try to cast an object to a type that cannot be casted. That is, to a subclass of which it is not an instance (to quote the documentation). e.g.:  Object o = new Double(3.); Double d = (Double) o; // Working cast String s = (String) o; // ClassCastException   And it seems I can do this. If a was just a T instead of an array T[], we can get a and cast it without a problem. Why do arrays break this?  Thanks.


What does the American idiomatic expression "2 x 4"  exactly mean? I've read a very interesting book by Father Donald H. Calloway, No turning back  (an autobiography and a conversion story), and chapter 10 is entitled "The divine 2 x 4". Could that mean the divine surprise, the divine intervention?

What does this sentence mean?     This observation hit me like a two-by-four   .


Basing this question on :     This is just a matter of simple math.      Saving accounts earn less than 1% per year.      CDs usually pay less than 2.75% per year.      Inflation is 1.9%-2.9% so deduct that.      401ks well invested can yield 4%-7%      The only thing worth investing in is a ROTH IRA or a no-load mutual   fund invested in an indexed fund of the DOW or S&P 500.   The Roth IRA account is good, I suppose, because of the tax free / deductible nature of withdrawing and contributing to the account.  However, why a no-load mutual find invested in an indexed fund of the S&P? Is it because you don't have to worry about figuring out how to diversify your portfolio because the index fund already takes care of that?  I'm skeptical of this answer. If you disagree, what do you think is a better strategy?

I use the quotations because generally the people touting these the most (John Bogle) are also ones selling the index funds. Being biased doesn't mean they're wrong, but it does mean they may not be telling the whole truth.   I understand the idea that index funds are better than managed accounts. Lower fees, probably better returns, etc. etc., but generally when this topic is discussed those are the only two options considered as if they were the only investment options out there. I also agree that they probably make a lot more sense as "fire and forget" type investments for people to invest as passively as at all possible.   But are investment funds really all that much better than just buying stocks for long term investing? Index fund fees may be incredibly low, but they're still yearly fees. Whereas with a stock you can (in theory) purchase a significant ownership stake in a company for $5 and it will cost you another $5 to divest. (Oversimplification, I know.)  Also major index funds may represent a more diverse investment, also in theory, but take for instance the S&P500 where 50 companies make up about half the market cap.  Why would it not make more sense to invest in a handful of these heavyweights instead of also having to carry the weight of the other 450 (some of which are mostly just baggage)?  Even Warren Buffet has been touting the index fund for a while now, but I haven't heard that Berkshire Hathaway has major holdings in an S&P500 index fund. So it seems like there's more to the story.   Where do you think the tipping point really is here?  Edit: had to be away from the computer most of the day. Don't mean to insinuate at all that index funds are bad. Just questioning whether they're the right call for someone willing to be active enough to check their investments a few times a year.   Edit2: Just because it seems like some people may still be misunderstanding me... the comparison that this entire question revolves around is long-term, mostly passive invesments in companies rather than almost all the eggs in the index fund basket. This may be a better way to think about it rather than my question of picking stocks... ie: "[PickaCompany] has historically done pretty well, their business models seems pretty good, people like their product, I expect them to continue making profit for a while, they have a large customer base and a good share of the market in their industry, they seem like a good investment." Oversimplification by far, but it's generally these things that put companies in index funds and at the top.


Im trying to use -exec to invoke a sed statement below: find '$path' -mtime +$daysold -exec sed -E -f redact.sed file.txt {} \;. what does {} do? and what goes inside {}?

I find myself constantly looking up the syntax of  find . -name "FILENAME"  -exec rm {} \;   mainly because I don't see how exactly the -exec part works. What is the meaning of the braces, the backslash and the semicolon? Are there other use cases for that syntax?


While reviewing some quantum mechanics, I cam across a very interesting situation.  For a potential barrier, if a particle has an energy $E$ less than the potential barrier $V_0$, it is possible to measure it inside the potential barrier or the classically forbidden region quantum mechanically.  But, if we calculate reflection and transmission coefficients for the wave, we find out $R=1$ and $T=0$ which means the wave will be fully reflected and no transmission will take place. But still there is probability of finding it inside the potential barrier. How?

I understand that if a particle approaches a finite potential barrier of height $V_0$ with energy $E < V_0$, there is still a finite probability of finding the particle on the other side of the barrier due to quantum tunneling.  My question is, since the wavefunction is nonzero inside the barrier region, is it possible to actually make a position measurement and locate a particle inside the barrier?  I mean, if we can say that "there is a nonzero probability that the particle is inside the barrier", surely this would suggest we can do so?  If not, why not? Am I understanding the whole wavefunction/probability distribution thing right?


I've got a float value and i need to have only two decimals after comma. I'm using this code:  public static float getWhatINeed() {   StatFs statFs = new StatFs(Environment.getDataDirectory().getAbsolutePath());   float total =        ((float)statFs.getBlockCount() * statFs.getBlockSize()) / (1073741824);   return total; }   And it returns for example: 12.552425 in a textview. I need display something like: 12.55 that is enough for me. I saw this:   String s = String.format("%.2f", 1.2975118);   somewhere but I can't use it in my case because I use a float value and I need to use float. How could I solve this?

What I would like is a method to convert a double to a string which rounds using the half-up method - i.e. if the decimal to be rounded is 5, it always rounds up to the next number. This is the standard method of rounding most people expect in most situations.  I also would like only significant digits to be displayed - i.e. there should not be any trailing zeroes.  I know one method of doing this is to use the String.format method:  String.format("%.5g%n", 0.912385);   returns:  0.91239   which is great, however it always displays numbers with 5 decimal places even if they are not significant:   String.format("%.5g%n", 0.912300);   returns:  0.91230   Another method is to use the DecimalFormatter:  DecimalFormat df = new DecimalFormat("#.#####"); df.format(0.912385);   returns:  0.91238   However as you can see this uses half-even rounding. That is it will round down if the previous digit is even. What I'd like is this:  0.912385 -> 0.91239 0.912300 -> 0.9123   What is the best way to achieve this in Java?


I have a apex Class which calls external ERP system and create/updates records there. The apex Class is like below  public class createSegment {     public class getAzureToken{         public  String getToken(){             String clientId = 'xxxx';             String clientSecret = 'xxxx';             String tenant_id = 'xxx';             String resource = 'https://dev.dynamics.com';              String reqbody = 'grant_type=client_credentials&client_id='+clientId+'&client_secret='+clientSecret+'&tenant_id='+tenant_id+'&resource='+resource;              Http h = new Http();             HttpRequest req = new HttpRequest();             req.setBody(reqbody);             req.setMethod('POST');             req.setEndpoint('https://login.microsoftonline.com/xxxx.org/oauth2/token');             HttpResponse res = h.send(req);              deserializeResponse resp1 = (deserializeResponse)JSON.deserialize(res.getbody(),deserializeResponse.class);             String atoken = resp1.access_token;             return atoken;         }     }      public class JSON2Apex {         public String dataAreaId;         public String SegmentCode;          public JSON2Apex parse(String json) {             return (JSON2Apex) System.JSON.deserialize(json, JSON2Apex.class);         }     }      public Integer createSeg() {         JSON2Apex js = new JSON2Apex();         getAzureToken gt= new getAzureToken();          js.dataAreaId = 'xxxxx';         js.SegmentCode ='Test from SF-Test1';          String jsonBody = json.serialize(js);          String bearerToken = gt.getToken();          Http http1 = new Http();         HttpRequest req1 = new HttpRequest();          req1.setEndpoint('https://dev.dynamics.com/data/Acc');         req1.setMethod('POST');         req1.setTimeout(20000);         req1.setHeader('Authorization','Bearer '+bearerToken);         req1.setBody(jsonBody);         req1.setHeader('Content-Type', 'application/json;charset=UTF-8');         HttpResponse res1 = http1.send(req1);         return res1.getStatusCode();       }     public class deserializeResponse         {             public String token_type;             public String expires_in;             public String ext_expires_in;             public String expires_on;             public String not_before;             public String resource;             public String access_token;         } }   For POC I have just hard coded the values. This works perfectly fine when I tried to execute is through Anonymously. Now I am trying to call this Apex Class from the Trigger like   trigger createSegments on Account (after insert) { createSegment h = new createSegment(); h.createSeg();        }   When the trigger is executed I get Error: Invalid Data. Review all error messages below to correct your data. Apex trigger createSegments caused an unexpected exception, contact your administrator: createSegments : execution of AfterInsert caused by: System.CalloutException: Callout from triggers are currently not supported.: Class.createSegment.getAzureToken.getToken: line 16, column 1  I tried to use the @future (callout=true) looks it works only with static method.Can anyone please help me how to handle this issue.

I have a trigger on the Custom Object that calls a class. That class makes an HTTP GET request to a Web Service.  However I get the following error:  Callout from triggers are currently not supported.  How can I get data to an external Web Service using Apex code?  However i can use @future method but it can only be support void and this method cannot return results, i need to be able to send data to external ervice and receive acknowlegements from it.


I have included an LWC component inside a VF page through $Lightning.createComponent. As per my requirement I need to call a javascript function on parent VF page on click of a button on LWC component. my VF page: <apex:page>     <script>         function callMe(someParam) {}                         $Lightning.use("c:myApp", function() {             $Lightning.createComponent("c:myLWCComp",               "LightningComponentid",               function(cmp) {               });         });      </script>    </apex:page>  my LWC Comp: <template>     <lightning-button label="Call Vf Method" onclick={callVfMethod}></lightning-button> </template>  In above example. On click of "Call Vf Method" button on LWC I want to call "callMe" method on parent Visualforce page. Also I want to pass some value as parameter. Please note that I these pages and components are accessed inside community.

I am adding an LWC component in visualforce and need to add a handler for an event fired in the LWC component on the visualforce page. When googling all I can find is examples of how to do this with aura component using application events. LWC controller: handleSearchClick() {              const searchinfo = {          shipper: this.shipper,         system: this.system,         product: this.product,         status: this.template.querySelector('c-lwc-multi-select').value(),         period: this.period       };     this.dispatchEvent(new CustomEvent(         'dosearch',          {             detail: { data:  searchinfo},             bubbles: true,             composed: true,         }     ));     console.log({ 'lwcNominationSearch searchinfo': searchinfo }); }  AURA app: <aura:application extends="ltng:outApp" access="GLOBAL"> <aura:dependency resource="c:lwcNominationSearch" /> <aura:dependency resource="markup://force:*" type="EVENT"/> </aura:application>  Visualforce: <div id="rcontainer"> </div>  <script>     $Lightning.use("c:NotificationSearch_ltngoutApp", function()     {         $Lightning.createComponent(         "c:lwcNominationSearch",         {},         "rcontainer",         function(cmp)         {             console.log('component created');              //$A.eventService.addHandler({ "event": "c:myEvent", "handler" : visualForceFunction})               $A.eventService.addHandler({                 event: 'dosearch',                 handler: function (event) {                          console.log("vf event success");                 }             });          });     }); </script>


I have an integer variable which casts into a floating point number as soon as i divide it. I need to stop this from happening  I've tried explicitly casting the variable after declaring it using the int() function but it still converted to a float as soon as i divided it  x = 5 int(x) x = x/2 type(x)   I expect the output of x/2 since its an integer but the output is 2.5, and when i run it through the type() function it returns a float

Is there a benefit to using one over the other? In Python 2, they both seem to return the same results:  >>> 6/3 2 >>> 6//3 2


In the notes I'm following to understand the proof that $L \vDash GCH$, there is this crucial following passage:     "Let $A \subseteq X$. There is some $\alpha$ such that $A ∈ L_\alpha$ , and it suffices to show that the least such $\alpha$ is strictly smaller than $\kappa^+$ . Because then $\mathcal{P}(X) \subseteq L_{\kappa^+}$"   It is probably very simple, but why every $A \in L_\alpha$ where $\alpha < \kappa^+$ implies that $P(\kappa) \subseteq L_{\kappa^+}$? My doubt is because $sup\{\alpha: \exists A  \subseteq \kappa \; A \in L_\alpha\}$ is not necessarily less than $\kappa^+$ if the $\alpha$ are.  Does $L$ "see" $|L_\alpha| = |\alpha|$?

I have a question about the proof of the following:     (Lemma 37) Assume $\mathbf V = \mathbf L$, and let $\kappa$ be a cardinal. Then   $\mathcal P (\kappa ) \subseteq L_{\kappa^+}$.   Assume we have proved the following:      (Claim 38) There exists a finite subset $T$ of $ZF + (\mathbf V =  \mathbf L)$ such that whenever $x$ is transitive and $\langle x, \overline{\in} \rangle \models T$ then there exists $\gamma \in  \mathbf{ON}$ such that $x = L_\gamma$.      (Lemma 35) Let $\alpha \in \mathbf{ON}$ and $x, a_0, \dots , a_{k-1}  \in L_\alpha$ and let $\varphi(z, a_0, \dots ,a_{k-1})$ be a formula   of $L_S$. Then there exists a $\beta > \alpha$ such that for every $z  \in x$: $$ \langle L_\beta , \overline{\in} \rangle \models \varphi  [z, a_0 , \dots, a_{k-1}]  \hspace{0.5cm} \text{ iff } \hspace{0.5cm}  \mathbf L \models \varphi [z, a_0 , \dots, a_{k-1}] $$     The proof in the book starts as follows: Suppose $\mathbf V = \mathbf L$ holds, let $\kappa$ be as in the assumptions of lemma 37 and suppose $\kappa \in \mathcal P ( \kappa )$. Fix an ordinal $\alpha > \kappa$ such that $y \in L_\alpha$. Since the theory $T$ of claim 38 is finite we can form the conjunction $\varphi$ of all sentences in $T$.   Question: But what is $T$? I know that it's the theory from claim 38 but it's not clear to me how we can use an unknown theory to prove lemma 37. And why do we take the conjunction over $T$?  Then the proof proceeds: By lemma 35,    Question: How does $\gamma < \kappa^+$ follow from $(2)$?  Many thanks for your help.


I am trying to prove that   $$e^{k+1} ≥ 3 + 3k + k^2$$ with, $$k>2$$  WhatI have done so far:  What we are trying to prove is that $$e^n≥1+n+n^2$$ is a true statement. Since $n=3$ holds, this is our base case. Then, the inductive hypothesis is: $$e^k≥1+k+k^2$$ Hence, I need to show $$e^{k+1}≥1+(k+1)+(k+1)^2=3+3k+3k^2$$ is a true statement.


I'm trying to prove that: $1^2 + 2^2 + 3^2 + ...+ n^2 = \frac{n(n+1)(2n+1)}{6}$  Defining the upper left side of the equation as $a_n$ I get:  $a_n - a_{n-1} = n^2$  Then, from the homogeneous eguation:  $a_n = C$  but while predicting the nonhomogeneous part as:  $a_n = xn^2 + yn + z$  and putting in into $a_n - a_{n-1} = n^2$ I get:  $2xn + y - 1 = n^2$  but it is not even close to giving me a right answer. What am I doing wrong?

I am just starting into calculus and I have a question about the following statement I encountered while learning about definite integrals:  $$\sum_{k=1}^n k^2 = \frac{n(n+1)(2n+1)}{6}$$  I really have no idea why this statement is true. Can someone please explain why this is true and if possible show how to arrive at one given the other?


Writing 0.001 to Postgres (9.1 to 9.3) via a .net data adapter results in a weird 0.00 value (in pgAdmin) that appears as zero but is not.  In fact, simple queries like SELECT 1/(SELECT "weird_field" ...) FROM ... correcly gives 1000.  More complicated queries (with division) surprisingly result in a division by zero error.  Also, ordering by in Navicat correctly shows those value between 0.0011 and 0.0009    We use Devart libraries to connect to the database, but the culprit seems to be the data adapter (or at least the combo of these two) because a simple direct query, still via Devart drivers, doesn't produce the same result.  Any idea on what's going on?  --  EDIT:  Type on DB is numeric, in the program is represented as double decimal.  pSQL prints this:   --            0.00 (1 row)  --  EDIT 2:  log_statement = 'all' gives a weirdER result:  UPDATE "TABLE" SET ... "WEIRD_FIELD"=$8 ... WHERE ...  DETAIL:  parameters: $1 = '7', $2 = '7', $3 = '18', $4 = '18', $5 = 'V03', $6 = 'Hz',                      $7 = 'Hz', $8 = '0.00', $9 = '0', $10 = '2', $11 = '0'   The parameter for the weird field is printed as zero (0.00), but clearly it is not...  Note that the value in the DataGridView populated by DataAdapter shows up the correct 0.001.  --  EDIT 3 (Maurice):  The issue with the Devart adapter seems to be fixed. Using the latest version, I no longer see the problem. I think it is related to this specific fix: 7.3.293 20-Nov-14: The bug with precision loss when working with PgSqlType.Numeric via the protocol 3 is fixed I upgraded my software using the latest Devart assemblies and now everything works as expected.

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


As someone from a scientific education background I can't help but notice that while, for example, biology is mentioned (and at times important) in the Harry Potter books and potions (akin to chemistry), there are no mentions made of math courses.   The logical explanation to me seems that as a writer, Rowling understood that for most of the target audience, maths won't be at the top of the list of interesting subjects.  However, is there an in-universe explanation as to why mathematics seems absent from the wizarding world?    What about Muggle-born kids who are taught and like math but are then shipped off to Hogwarts where, seemingly, math is a no-no?

I always wondered if children who graduate from Hogwarts have an education that is actually worth while in the real world.  Do the children learn math and English?  I can see History of Magic as practical. I know of Arithmancy, but that's the study of the magical properties of numbers, not math.   Since Hogsmead is one of the very last all-magical towns, it's a fair assumption that a majority of the students at Hogwarts will be living in non-magical towns or cities. If practical classes (like math or English) aren't taught, then how do these students function in the non-magical cities?


I've written a trigger that will add users to a public group but can't seem to get my test class to work. I have 100% code coverage but the test keeps failing with the Mixed DML Operation error.   Trigger:      trigger addintoPublicgroup on User (after insert, after update) {     AddUser.AddToGroups(trigger.newMap.keySet()); }   Class:  //This class is refrenced in the apex trigger Add to Group in order to add users automatically to public groups. public class AddUser{  @future public static void AddToGroups(Set<Id> userIds) {  //Get the groups that the user should be added to Group g=[select Id from Group Where DeveloperName='Coordinators']; Profile p =[select Id from Profile Where Name = 'Sesaco Coordinator'];   List<User> users=[Select Id,Name from user Where Id IN :userIds and user.ProfileId=:p.Id];   List<GroupMember>listGroupMember =new List<GroupMember>();    // loop the users that have been created  for (User user : users){       GroupMember gm= new GroupMember();        gm.GroupId=g.id;       gm.UserOrGroupId = user.id;       listGroupMember.add(gm);     }   insert listGroupMember; } }   Test Class:  @isTest public class addintoPublicgroup_Test {      static testMethod void AddToGroups(){      County__c cty = new County__c();         cty.Name = 'Whitman';         cty.State__c = 'WA';         cty.Planting_Area__c = '1';         insert cty;      Account act = new Account();         act.Name = 'Test Account2';         act.Account_Status__c = 'Active';         act.BillingCity = 'Pullman';         act.BillingState = 'WA';         act.BillingCountry = 'US';         act.Description = 'Go Cougs';         act.County__c = cty.Id;         insert act;      Contact con = new Contact();         con.FirstName = 'Test User';         con.LastName = 'Number One';         con.Email = 'testing222111@sesaco.com';         con.AccountId = act.Id;         insert con;          Profile p = [Select Id from Profile WHERE Name = 'Sesaco Coordinator'];          User usr = new User();         usr.FirstName = 'Test User';         usr.LastName = 'Number One';         usr.Email = 'testing222111@sesaco.com';         usr.Username = 'testing222111@sesaco.com';         usr.Alias = 'tester';         usr.ContactId = con.Id;         usr.ProfileId = p.Id;         usr.TimeZoneSidKey    = 'America/Denver';         usr.LocaleSidKey      = 'en_US';         usr.EmailEncodingKey  = 'UTF-8';         usr.LanguageLocaleKey = 'en_US';           try {             insert usr;         } catch (Exception e) {            System.debug('An error occurred');         }        } }   I believe I need to use a combination of System.RunAs and @future in my test class but am unfamiliar with either of those uses in a test class. Any help is appreciated!

In my test class i have the creation of a dummy custom setting and a dummy lead:  Group g1 = new Group(Name='group name', type='Queue');              insert g1;             QueuesObject q1 = new QueueSObject(QueueID = g1.id, SobjectType = 'Lead');              insert q1;       SetOwner__c mycs = SetOwner__c.getValues('standardset');               if(mycs == null) {                               mycs = new SetOwner__c(Name= 'CustomValues');                  mycs.OwnerId__c ='00520000000z3PrAAI';                  mycs.RecordtypeID__c='012L00000004QsrIAE';                  insert mycs;      Lead lead = createNewLead(u2.id);                           insert lead;   ERROR:  MIXED_DML_OPERATION, DML operation on setup object is not permitted after you have updated a non-setup object (or vice versa): SetOwner__c, original object: QueueSobject: []   I get this error because i am trying to perform DML on setup and non-setup objects in the same transaction.  Any solution for this problem?


I just found a typo in the Elections page:   This election is currently in the nomination phase.Nominations close in 6 days                                                    ^^                         ^^                                                   I need a space here!!      |                                                                              |                                              also a final dot here wouldn't hurt

reads:     This election is currently in the nomination phase.Nominations close in 7 days    The space after the S of “days” should be moved to just before the N of “nominations.” IMO, there should also be a period following “days.”


Consider an isosceles right-angled triangle as shown in the figure (top left). The length of its hypotenuse is $c$. The figure distinguishes both legs of the triangle, however, from now on let's assume, since it's an isosceles right-angled triangle, that $b=a$.  Now, let's build a stair on the hypotenuse with steps of height $\frac{a}{n}$, and width $\frac{a}{n}$. If $n=1$ we have the picture of the figure (top centre), in which $d=a$ and $e=a$. Here the length of the stair is $d+e=2a$. Notation: I will refer to each step in the stair as $s_k$ for some $k\in\mathbb N:0<k\leq n$. If we continue doing the same procedure, we have that for some $n\in\mathbb N$ that the lenght $\ell(n)$ of the stair is: $$\ell(n)=\sum\limits_{k=1}^n \text{lenght}(s_k) = \sum\limits_{k=1}^n2\frac{a}{n}=2a.$$ If we build a stair with infinitely small steps, why don't we end up with a straight line? Because if we did, we would be saying that $c=2a$, and by the pythagorean theorem we know that $c=\sqrt{2}a$. I appreciate your thoughts.

What is wrong with this proof?    Is $\pi=4?$


While I'm reviewing my profile, I did notice a strange behavior especially on my 0 votes questions:     As you can note here, 4 votes down on the 4 so different questions in 1 minutes, that target my 0 votes questions to be -1 fo all, which this is an annoying part here!  I don't really bother myself with this, but still, I want to understand how to prevent that or report that.  I tried to find a question similar to this, but I found nothing talking about this case exactly, (or I was searching for incorrect words).  Any explanation and how to report this? Especially that down caster seems smart guy trying to avoid the auto-detect system of stack overflow system.

I just noticed that I lost a bunch of points from my reputation score, and I used the "reputation" tab on my user profile page to try and track down the cause.  During my investigation, I noticed there was an unusual event of type "reversal". In the normal place of a question title, it says "voting corrected".     What does this mean, and what caused it?  Did I do something wrong? Why did I lose all of that reputation? Is the system punishing me for leaving too many good answers?  Is there any way to earn it back?


I can imagine this might be a duplicate, but even looking at the questions asked, I'm still not sure when I should use which or that.  I'm uncertain whether or not I should use 'that' or 'which' in my case.  If someone could point out what is the correct use (or even if both can be used), it would be really helpful.  In the following sentence, should it contain 'that' or 'which'?   The analysis does not contain a timeframe that/which specifies the amount of time required  for participants to synchronize to a metronome.

When is it appropriate to use that as opposed to which with relative clauses?


Could someone please help me understand why when we project a new sample in kernel PCA to an eigenvector $\alpha$, we normalize it by dividing the eigenvector $\alpha$ with its eigenvalue $\lambda$?  I understand that we need to normalize the eigenvector $V$ and hence the eigenvector $\alpha$ following the criteria described in Eq 9 of the following original paper: .  However, I couldn't figure out why we divide by $\lambda$ in the normalization (instead of e.g. $(\|\boldsymbol\alpha^{k}\|\sqrt\lambda)$  - see below for derivation)?  Eq.9 requires  $$1 = \lambda_k(\boldsymbol\alpha^{k*}\cdot\boldsymbol\alpha^{k*})$$  where $\boldsymbol\alpha^{k*}$ is the normalized $\boldsymbol\alpha^k$. Since $\boldsymbol\alpha^k\cdot\boldsymbol\alpha^k = \|\boldsymbol\alpha^k\|^2$,   $$\boldsymbol\alpha^{k*} = \frac{\boldsymbol\alpha^{k}}{\|\boldsymbol\alpha^{k}\|\sqrt{\lambda_k}}$$  Eq. 10 (projection of a test point $\boldsymbol\phi(\mathbf{x})$) becomes  $$(\mathbf{V}^{k*}\cdot\boldsymbol\phi(\mathbf{x})) = \sum_{i=1}^{l}\alpha_i^{k*} (\boldsymbol\phi(\mathbf{x}_i)\cdot\boldsymbol\phi(\mathbf{x})) = \frac{1}{\|\boldsymbol\alpha^{k}\|\sqrt{\lambda_k}}\sum_{i=1}^{l} \alpha_i^{k}(\boldsymbol\phi(\mathbf{x}_i)\cdot\boldsymbol\phi(\mathbf{x}))$$ $$= \frac{1}{\sqrt{\lambda_k}}\sum_{i=1}^{l} \alpha_i^{k}(\boldsymbol\phi(\mathbf{x}_i)\cdot\boldsymbol\phi(\mathbf{x}))$$  where $\mathbf{V}^{k*}$ is the normalized $\mathbf{V}^{k}$ and $\|\boldsymbol\alpha^k\| = 1$. But, I know that the above normalization is incorrect because instead of dividing by $\sqrt{\lambda_k}$, we should simply divide by $\lambda_k$. So, I am not sure where I am making mistakes here.  For a nice python implementation of kernel PCA and the normalization of the eigenvector, please refer to the following site:  You can go straight to  def project_x(x_new, X, gamma, alphas, lambdas):   to see that we need to normalize the $\alpha$ by dividing it with $\lambda$ in order to get the correct projection.  Update:  The above normalization is correct. The question was there because I misunderstood Sebastian's code.

Let $X_{N \times d}$ be the data matrix, where $N$ is the number of samples and $d$ the size of the features space.  Using kernel PCA (kPCA), one first computes a kernel matrix $K_{N \times N}$, and then, after its eigenvectors $E_{N \times N}$ have been computed, it is possible to project the data onto the first $c \leq N$ components as: $$X_\mathrm{projected} = KE_c,$$ where $E_c$ denotes first $c$ columns of $E$. Equivalently, in Matlab notation:  Projected_data = K*E(:,1:c);   The new projected data have now size ${N \times c} $.  I would like to know if it is possible to project an unseen data vector $x_{1 \times d} $ onto the previously computed principal components $E$. If it is possible, what is the correct procedure?


Why are the ads shown on SE about SE websites and its android app only? I don't think that'll earn SE something. I'd says that almost every time, the ad is about SE network website and only a few times about other websites like:ProofWiki, MIT OpenCourseWare, etc. So why is it so?

I once , but that was . Now, , and they have , but where's the business model? The  its own Q&A about its site (since it wasn't included in the ), and just about the only dig in there that halfway has merit is the business model dig:  We switched to a premium model to keep out of the Venture Capital business (been there, done that, got the t-shirt). Companies like StackExchange couldn't do it without the VC cookie jar. Where's the model? Huh, Spolsky? (I’m sorry. Did that slip out?)  It hurt, but I can't help but wonder if they're on to something.  How would Stack Overflow Internet Services pay back the VCs? Ad revenue alone?  There is only one 'paid' product, Stack Overflow careers, but it doesn't seem like that could sustain a business as large as Stack Overflow (Joel once mentioned on his blog that his jobs board brought in an extra million a year in revenue). So what does Stack Overflow do when the VC cash runs out? Is this a get-big-and-take-the-company-public maneuver? Is that the only viable business model for Stack Exchange? Edit: With the size of Stack Overflow's team, it isn't a stretch to say that payroll is at least $2 million  a year, probably as much as 4 when you think about benefits (average 120K for a developer in New York City; x2 for benefits/taxes/all-that-other-good-stuff). Office space can't be cheap, so how long does $6 million last before you need another VC infusion?


If for example I have a value in cell A1, lets say 2  What I want to do is multiply that cell by 0.75 but in the same cell  I don't want to have to put a formula in B1 such as =(A1*0.75), because I already have a value in B1 and I don't want to have to insert a new column.  if I highlight cell A1 and put the formula =(A1*1.333) into it the value becomes 0.00  Can what I'm asking be done? or would I need to create a macro?  Any help would be appreciated.  Thanks

Another excel question. I'm using Excel 2010.  If for example I have a value in cell A1, lets say 2.59  What I want to do is multiply that cell by 1.333 but in the same cell  I don't want to have to put a formula in B1 such as =(A1*1.333), because I already have a value in B1 and I don't want to have to insert a new column.  if I highlight cell A1 and put the formula =(A1*1.333) into it the value becomes 0.00  Can what I'm asking be done? or would I need to create a macro?  Any help would be appreciated.  Thanks


My Bars on top and at left disappeared. I can now only right click and choose - change desktop background - Pressing Ctrl+Alt+T bring terminal out. Problem is I know nothing about it. There is now only my wall paper on the screen.

When I login, nothing happens.   I am presented with my desktop wallpaper.    No Dash, no Launcher, nothing.


Using ed put character # to the beginning of lines 10 to 20 in file /etc/passwd. Solution is the following  ed /etc/passwd <<\END 10,20s/^/#/ %p Q END   my question is that what does << means here and \ before END and why we use it. Do we have to use it all the time or not?

I often see tutorials online that connect various commands with different symbols. For example:  command1 |  command2 command1 &  command2 command1 || command2     command1 && command2   Others seem to be connecting commands to files:  command1  > file1 command1  >> file1   What are these things? What are they called? What do they do? Are there more of them?    .


i have this string pattern:  Name: bondy address: kuta, bali age: 20   i want to get the name value of Name i did regex like this:  /(?<=Name:)(.*)(?=[\n\r])   but somehow it reads until the last newline?  demo:

I have this gigantic ugly string: J0000000: Transaction A0001401 started on 8/22/2008 9:49:29 AM J0000010: Project name: E:\foo.pf J0000011: Job name: MBiek Direct Mail Test J0000020: Document 1 - Completed successfully  I'm trying to extract pieces from it using regex. In this case, I want to grab everything after Project Name up to the part where it says J0000011: (the 11 is going to be a different number every time). Here's the regex I've been playing with: Project name:\s+(.*)\s+J[0-9]{7}:  The problem is that it doesn't stop until it hits the J0000020: at the end. How do I make the regex stop at the first occurrence of J[0-9]{7}?


I want to be able to see a list of all the questions I have ever asked on the whole of the platform.  This is because there is useful material and references in the answers and comment posts.  I really need a list of my questions in one place!

I am writing several papers in which I use answers which I received in various StackExchange websites. Naturally I would like to acknowlege and thank the SE members that gave the useful answers. But there are many such answers, and each answer is relevant to a different paper.   So, I would like to download all the questions that I asked in the various SE websites, including the answerer names, to an Excel worksheet in which I can organize the questions by subject.  Is this possible?


Let $Tor(G) = \{ g \in G | \exists n >0 , g^n = e \}$ of a group $G$ , give an example to $G$ such that $Tor(G)$ is not sub group ?  Easy to prove that $G$ must be non-Abelian and infinite in size, so i thought of matrix but i don't have concrete example

In a question from an exam in an undergraduate group theory course, we were asked to prove or disprove that the set of all Torsion elements of a group is necessarily a subgroup.  I knew that the set of Torsion elements is closed under the inverse operation, but was later told that it is not closed under multiplication, therefore disproving the claim. However, I couldn't find any examples of a group $G$ and two elements $a,b$ such that both $a$ and $b$ have a finite order, but $ab$ doesn't. I know that for this to happen $G$ must be an infinite and non-Abelian group, but still couldn't find a valid example.   What are some examples of groups/elements fulfilling the aforementioned property?


I have a dataset with over 20 variables. Some of them are numerical and some of them are categorical:  C          <- c(4, 8.5, 2, 5, 6) N          <- c(0.4, 0.1, 0.5, 1.2, 1.1) moisture   <- as.factor(cbind("dry","dry","dry","wet","wet")) vegetation <- as.factor(cbind("forest", "wetland", "field", "forest", "wetland")) df         <- data.frame(C,N, moisture,vegetation)   I want to know the pairwise correlation between each of these variables. I found two solutions for this: rcorr() and hetcor(). While rcorr gives me Pearsons's product-moment correlation or Spearman's rho rank correlation including p-values, hetcor() offers me the discrimination into polyserial and polychoric correlations, but no p-values.  I would use rcorr with Pearson which has the advantage of also including p-values, but I am not sure if it qualifies for this sort of data. Can I still talk of correlations in this case or do I need to talk about significance of association? If I use hetcor I seem to gain the advantage of it being applicable for categorical data, but I don't get the p-values.

I have a dataframe with many observations and many variables. Some of them are categorical (unordered) and the others are numerical.  I'm looking for associations between these variables. I've been able to compute correlation for numerical variables (Spearman's correlation) but :   I don't know how to measure correlation between unordered categorical variables. I don't know how to measure correlation between unordered categorical variables and numerical variables.   Does anyone know how this could be done? If so, are there R functions implementing these methods?


$$\int\frac{\ x^2+20}{{(x\sin x+5\cos x)}^2}\mathrm{d}x$$ What should be the first thought for such a question?

How do we integrate  $$\int \frac{x^2+20}{(x \sin x+5 \cos x)^2}dx$$  Could someone give me some hint for this question?


I have to calculate this limit whitout using L'Hopital's rule or Taylor polynomials: $$ \lim_{x \to 0} f(x) = (1+\frac{x}{2})^{\frac{1}{x}} $$ I know how to make it using L'Hopital and that the result is $ e^{\frac{1}{2}} $ ,but I'm getting nowhere when I try without it. Any advice?

Title is the question itself.  How can I show below without L’Hospital’s Rule  $$ \lim_{x\to \infty} ( 1 + x )^\frac{1}{x} = 1 $$


Between two junction stations, there are 12 sub stations. In how many ways a train can stop at 4 of these sub stations such that no two of these halting sub stations are consecutive?  I have no idea from where to start this problem....been thinking of it for quite some time....One possible way would be to subtract the no. of ways in the train halts at at least 2 consecutive stations then add back no. of ways it can stop at at least 3 consecutive stations and finally subtract the no. of ways it can stop at exactly four consecutive stations; from the total no. of ways it can stop at four stations out of the 12 given stations....  But apparently the answer I get from this is wrong...can anyone help me out?? Thanks in advance!!

There are 12 intermediate stations on a railway line between 2 stations. Find the number of ways a train can be made to stop at 4 of these so that no two stopping stations are consecutive.   My attempt:  Initially I found the maximum allowed stop number for the first stop that satisfies the consecutive station condition.  $$A \quad 1 \quad 2 \quad 3 \quad 4 \quad 5 \quad 6 \quad 7 \quad 8 \quad 9 \quad 10 \quad 11 \quad 12 \quad B$$  I can have a stop at stations 8, 10, 12. Hence the train can travel a maximum of 6 stations before coming to its first stop, so number of ways $= 6 \cdot 1 \cdot 1 \cdot 1 = 6$.  Then I shift the first stop to station number 5. Now I have 5 options for stop 1 and 2 possible options for any of the next three stops. Hence number of ways $= 5 \cdot 2 \cdot 3 \cdot 1 = 30$.  Again, I shift the first stop to station number 4. Now I have 4 options for stop 1 and 3 possible options for any of the next 3 stops. Hence number of ways $= 4\cdot 3\cdot 3 = 36$.  Continuing the same logic, I arrive at an answer of 156. But the answer I have with me is 126.  Help appreciated. Thanks in advance.


I'm fairly new to blender so I don't for sure that what I'm doing is correct. But I need recreate this jar.  I got as far as the overall shape. But now I have to put the dents at the bottom in and I don't know how to best do that.  I've tried to make a displacement map with Photoshop but that turn the render very dark, almost black even. It seems like a lot of shading issues are happening.  How do i get the dents correct without artifacts and render issues?

I'm trying to learn blender, and for fun trying to make a model of a bottle. The bottle shape is no problem, but the bottle has a special pattern in its material that needs to be cut out from it. How can i do this? I tried many different ways but nothing worked very well. I've attached an image of bottle in Blender. The pattern I want to cut out is the photo I've used as background image.


I know no descriptive set theory. I've stumbled on something that must be well known, being so simple. But it contradicts something I've been told by smart people; the question is whether it's well known (or at least known).  A complete version of this post would be a little long. It seems clear to me that anyone who knows the answer is going to understand what I mean by the standard this and the usual that; if not I can clarify.  Context. Say $G$ is a group and $S\subset G$. There are at least three ways to say what $H$, the subgroup of $G$ generated by $S$, is:   Let $S_0=S$, and let $S_{n+1}$ be $S_n$ together with all the $xy$ and $x^{-1}$ for $x,y\in S_n$. Then $H=\bigcup_{n=0}^\infty S_n$. (I call this the bottom-up construction.) $H$ is the set of all words in the elements of $S$. $H$ is the intersection of all the subgroups of $G$ containing $S$ (this I tend to think of as "top-down".)   Not that anyone would ever use (1) in this context. But now let's say $S\subset P(X)$, the powerset of $X$, and we want to describe $A$, the sigma-algebra generated by $S$. The analogue of (3) is what you see in every book on measure theory; some books include the transfinite-recursion analogue of (1) when they want to show that the Borel sets on the line have cardinality $c$. For some time I've speculated on whether there was something like (2) here.  There is.   (2') The elements of $A$ are exactly the roots of the trees $T$ such that $T$ is well-founded, every node of $T$ is a subset of $X$, every terminal node is an element of $S$, and every other node has either one or countably many subnodes; if a node $E$ has one subsnode $F$ then $E$ is the comlement of $F$, while if $E$ has countably many subnodes it is the union of the subnodes. (Taking advantage of the arity to avoid coloring the nodes to say which operation we're using is probably in poor taste, sorry.)  The proof that this works is totally elementary and straightforward from the definition of $A$ as the intersection of all sigma-algebras containing $S$ - no need to confuse the poor students with ordinals. And one can use it to show, for example, that the Borel sets on the line have cardinality $c$.  I'd be certain that this was perfectly well known except that smart people have told be that the only way to show the Borel sets have cardinality $c$ is transfinite induction.  Hence the question: This actually is standard, those guys were just unaware of it as I was until yesterday, right?

I am struggling to understand why it should be that the $\sigma$-algebra of subsets of $X$ generated by $\mathcal{A}$ should be the smallest $\sigma$-algebra of subsets of $X$ including $\mathcal{A}$.    Let me try to elucidate my understanding of the topic, in the hope that somebody patient and kind might be able to fill in the gaps.  If $X$ is a set, and $\mathcal{G}$ is any non-empty family of $\sigma$-algebras of subsets of $X$, then I am very happy that   $$ \bigcap \mathcal{G} := \left\{ E : E \in \Sigma, \forall \Sigma \in \mathcal{G} \right\},$$  the intersection of all the $\sigma$ algebras belonging to $\mathcal{G}$ is a $\sigma$-algebra of subsets of $X$.    Now, if $\mathcal{A}$ is any any of subsets of $X$, then defining  $$ \mathcal{G} := \left\{ \Sigma : \Sigma \ \textrm{is a } \sigma \textrm{-algebra of subsets of } X, \mathcal{A} \subseteq \Sigma \right\},$$  then we have by definition that $\mathcal{G}$ is a family of $\sigma$-algebras of subsets of $X$; also, since $\mathcal{P} X \in \mathcal{G}$ we have that it is non-empty. So $\Sigma_{\mathcal{A}} := \bigcap \mathcal{G}$, called the $\sigma$-algebra of subsets of $X$ generated by $\mathcal{A}$, is a $\sigma$-algebra of subsets of $X$. Because $\mathcal{A} \subseteq \Sigma$ for every $\Sigma \in \mathcal{G}$, we have $\mathcal{A} \subseteq \Sigma_{\mathcal{A}}$; thus $\Sigma_{\mathcal{A}}$ itself belongs to $\mathcal{G}$.  However, I cannot get my head around why it should be that $\Sigma_{\mathcal{A}}$ should be the smallest $\sigma$-algebra of subsets of $X$ including $\mathcal{A}$, perhaps because I am not entirely sure what this statement means explicitly (namely, I have problems interpreting 'smallest' and 'including')! I'd be very relieved if someone could try to explain this to me as it has been bugging me for a week now; I have a feeling that it might rely heavily on the $\bigcap$, but I'm not sure exactly how...


In the given matrix, only one eigen value is real. What is that eigen value ?  \begin{bmatrix}  1&  5&  4&  3& 2\\   2&  1&  5&  4& 3\\   3&  2&  1&  5& 4\\   4&  3&  2&  1& 5\\   5&  4&  3&  2& 1 \end{bmatrix}    Is there any small approach ?

Let $A$ be an $n \times n$ matrix.  $i)$Prove that if the sum of each row of $A$ equals $s$, then $s$ is an eigenvalue of $A$.  $ii)$Prove that if the sum of each column of $A$ equals $s$, then $s$ is an eigenvalue of $A$.  I think that being an eigenvalue of $A$ implies that $sv=Av$ for some vector $v$. Furthermore, I know that $[a_i] = s$ if we let $a_i$ denote the i-th row of $A$. However, I do not seem to be able to find a link between these two facts. Could anyone please help me out?


I noticed a difference in the behaviour of the String.replace(CharSequence, CharSequence) between java 12 and 13. java 12 and earlier: System.out.println("String"=="String".replace("g","g")); //false  java 13 and later: System.out.println("String"=="String".replace("g","g")); //true  Found that this is probably due to:  Is this unexpected behaviour? Yes, I'm aware of the equals method.

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I was said that can exists simple algebras $A$ that are not semi-simples in the following sense:   $A$ is simple, i.e. doesn't have non trivial ideals; $A$ is not semi-simple, i.e. is not a semi-simple module over itself.   Does anybody has an example? Thanks in advance

A simple module is a semisimple module .     A module $M$ is called semisimple if every submodule is a direct summand of $M$   Since a simple module has $\{0\}$ and $M$ as its submodules so it is semisimple.  But why is  a simple ring not semisimple because a      A ring is semisimple if it is semisimple as a module over itself   How to construct such a ring?When will the result hold?


I came across the following statement, which I do not see how to prove it: $$\lim_{\epsilon \to 0} \frac{\epsilon}{x^2+\epsilon^2} =\pi \delta(x)\,.$$ Any ideas how to proceed?

Show that :   $\lim_{\epsilon \rightarrow  0} \frac{\epsilon}{x^2+\epsilon ^2} = \pi  \delta (x)$  Where $\delta (x)$ is the dirac-delta function.  I can't show that the integral of this over all $x$ is $\pi$


I have a date string in following format 2011-03-07 how to convert this to datetime in python?

I've got a huge list of date-times like this as strings:  Jun 1 2005  1:33PM Aug 28 1999 12:00AM   I'm going to be shoving these back into proper datetime fields in a database so I need to magic them into real datetime objects.   This is going through Django's ORM so I can't use SQL to do the conversion on insert.


I want to display title in the browser using title tag. I used   <script>$(document.title).html('title');</script>

I have a webpage that implements a set of tabs each showing different content. The tab clicks do not refresh the page but hide/unhide contents at the client side.  Now there is a requirement to change the page title according to the tab selected on the page ( for SEO reasons ). Is this possible? Can someone suggest a solution to dynamically alter the page title via javascript without reloading the page?


I would like to concatenate multiple parameters to a single string in bash like this: $ ls -latr $ cp -Rv directory1 directory2  The best I can do is something like this: while (( ${#} )) do     case "${1}" in         "-h" | "--help")             getScriptUsage             exit 0             ;;          "-i" | "--include-alpha-builds")             include_alpha_build_versions="true"             ;;          "-r" | "--redownload")             removeAllFiles             ;;          "-t" | "--torbrowser-version")             tarball_filename_version="${2}"             shift             ;;          "-v" | "--version")             getVersion             ;;          *)             getScriptUsage             /bin/echo -e "\e[01;31mParameter '${1}' not found.\e[0m"             exit 1     esac      shift || break done   But with that, I can only append the parameters: $ torbrowser -i -r -t 9.5  Might be off topic: I also would like to be able to mix parameters around, like in cp: $ cp directory1 directory2 -Rv $ cp -Rv directory1 directory2

Say, I have a script that gets called with this line: ./myscript -vfd ./foo/bar/someFile -o /fizz/someOtherFile  or this one: ./myscript -v -f -d -o /fizz/someOtherFile ./foo/bar/someFile   What's the accepted way of parsing this such that in each case (or some combination of the two) $v, $f, and  $d will all be set to true and $outFile will be equal to /fizz/someOtherFile?


If I have just the #index on my body element, the length method gives me the correct answer of 1. But if I have a second ID on this body element the length method gives me 0. Whats wrong with that?  $("#index").length   You can test it here. Just remove the .removeme from the body tag and try the command in the developer console again.    Any ideas or suggestions?

I understand that an id must be unique within an HTML/XHTML page.  My question is, for a given element, can I assign multiple ids to it?

   I realize I have an easy solution with simply using a class. I'm just curious about using ids in this manner.


I am trying to change a blockdata as an entity (ArmorStand, but at his x y and z) it doesn't work! Any solutions?  /execute @e ~ ~ ~ detect ~ ~ ~ minecraft:dropper 0 {Items:[0:{Slot:4b,id:"minecraft:stone",Count:1b,Damage:0s}],id:"Dropper"} /blockdata ~ ~ ~ {......}

I was using this command to use a custom crafting table:  /execute @a ~ ~ ~ detect ~ ~-1 ~ dropper 1 {Items:[{id:minecraft:blaze_rod,Slot:1b,Count:1b,Damage:0s},{id:minecraft:blaze_rod,Slot:4b,Count:1b},{id:minecraft:stick,Slot:7b,Count:1b}]} /scoreboard players set @p LSC 1   But I get this error message when I stand on a dropper with these items:     Failed to execute '{Items:[{id:minecraft:blaze_rod,Slot:1b,Count:1b,Damage:0s},{id:minecraft:blaze_rod,Slot:4b,Count:1b},{id:minecraft:stick,Slot:7b,Count:1b}]} /scoreboard players set @p LSC 1' as TrevMCC38   By the way, Im in 16w06a


Since there are  complex numbers (2 dimensions) and quaternions (4 dimensions), it follows intuitively that there ought to be something in between for 3 dimensions ("triernions").   Yet no one uses these. Why is this?

I am trying to solve the following exercise:     Prove that complex multiplication does not extend to a multiplication   on $\mathbb R^3$ so as to make $\mathbb R^3$ into a real division   algebra.   I am aware of Frobenius' theorem that there are only three finite dimensional real associative division algebras. But the exercise would be pointless if the theorem was assumed.   Let $x,y \in \mathbb R^3$. Since $x y$ has to extend the complex multiplication:  $$xy = (x_1y_1-x_2y_2, x_1y_2 + x_2 y_1, ?)$$  I have no idea how I can proceed from here. Could someone tell me how to do this? It should be easy as the other exercises I did so far were also easy.


I am building a database and I want to be able to store a user input filepath and have it available as a variable even after the application is closed and restarted to prevent retyping the path with each launch.

I want to create an ini file to store some settings for my application. Is it a good idea to find where the jar file is located and create an ini file there? If yes, then how can I find the location of the jar file?   But if you know a better solution for something like this, I would like to hear some of them.  EDIT: I'm using mac and I want to run the same application in windows. I could write something in the System.getProperty("user.home") directory, but I want to keep the system clean, if the user decides to remove the app. There is no a better way to store the settings file, for example in the same directory with the application?


I want to know how I can easily start a server that only me and my girlfriend who lives a few states away can play on.

I would like to create a minecraft server for me and and my boyfriend to play on.  How do I set it up? Do I need any additional software? Do you have some links to walkthroughs or tutorials?  I have tried to set this up a few times but have failed every time.


Let $M$ be a compact 2-manifold with positive sectional curvature. Show that any two closed geodesics of $M$ must intersect. The familiar example is $S^n$, where the closed geodesics are great circles, where any 2 geodesics must intersect. I'm wondering if there is a technic that transforms any 2-manifold with positive sectional curvature continuously into $S^n$, while in the mean time preserving geodesics? Specifically, let $c$ be the closed geodesic, $M_t$ be the transformation of $M$ with parameter $t\in [0, \infty)$, and let $c_t$ be the image of $c$ in $M_t$. Is is possible to find $M_t$ such that $c_t$ are geodesics, and $\lim_{t\rightarrow \infty} M_t \approx S^2$? If such transformation exists then the problem is trivial.

Suppose $M$ is a connected, compact orientable 2-dimensional Riemannian manifold, with positive Gaussian curvature. I'd like to show that two non-self-intersecting closed geodesics must intersect each other.  I tried to use Gauss-Bonnet Theorem to prove this, but I wasn't successful. Can somebody help me ? Thank you.


I was thinking of atoms. Usually atoms have same amount of electrons and protons. While electrons are negatively charged and Protons are positively charged. As we know from coulomb's law that positive and negative charge always attracts and (positive and positive) or (negative and negative) distract. So, they should collide inside atom also. I was searching on Google little bit. I found in Google that while electrons and protons come closer and closer they form mesons. While I was writing the question I found a related question to this in .  An electron can't be compared to a planet, and must instead be thought of as a kind of cloud of probability  Electron is particle and it has wavelike behavior also. Is it the reason of not to collide? I didn't get the answer of Quora. While it is particle it must have to collide. I found another related question in .  They do collide. But it's not like cars crashing and smashing each other up on the highway. Their quantum mechanical wavefunctions overlap and the electrons do in face settle in with wavefunctions that are centered on the nucleus.  If they collide than why atoms aren't vanishing? What type of collision is happening inside Atom? As I wrote earlier if they collide, they form mesons that's what I got in Google. But, I am unable to understand the collision inside Atom? What's happening right there?

I'm having trouble understanding the simple "planetary" model of the atom that I'm being taught in my basic chemistry course.   In particular,    I can't see how a negatively charged electron can stay in "orbit" around a positively charged nucleus. Even if the electron actually orbits the nucleus, wouldn't that orbit eventually decay?  I can't reconcile the rapidly moving electrons required by the planetary model with the way atoms are described as forming bonds. If electrons are zooming around in orbits, how do they suddenly "stop" to form bonds.     I understand that certain aspects of quantum mechanics  to address these problems, and that there are  of atoms. My question here is whether the planetary model itself addresses these concerns in some way (that I'm missing) and whether I'm right to be uncomfortable with it.


I would like to fit 2 plots next to each other on a page. These 2 plots need to be large enough, to the numbers on them can be read.  Currently, I use the following to add the images:   \usepackage{graphicx}  \includegraphics[scale=0.5]{./plots/fig1.png}  \includegraphics[scale=0.5]{./plots/fig2.png}   But this leads to the following layout:    How can I change this so that the left margin is ignored and these 2 images are centered? Or any other suggestion on how I can create a nice looking layout, since I'm quite new to Latex.  EDIT:   To download  and . This is there original size.

I have a figure that is wider than the \textwidth of my document. (I don't want to change the \textwidth.) As a result, the leftmost part of the figure is flush with the left margin, while the rightmost part spills into the right margin too much. I'd like to center the figure, so that it will exceed the \textwidth equally on both sides.


Convergence of {$f_n$} to $f$ in $L_1 (\mu)$ are equivalent to each subsequence {$g_n$} in {$f_n$} contains a subsequence {$g_{nk}$} convergent to $f$ in $L_1 (\mu)$  The left side can easily deduce the right side. But how to prove the opposite direction.  Thank in advance.

Is the following true? Let $x_n$ be a sequence with the following property: Every subsequence of $x_n$ has a further subsequence which converges to $x$. Then the sequence $x_n$ converges to $x$.  I guess that it is true but I am not sure how to prove this.


I have a function of the following form:  $J = \|W^TW-I\|_F^2$   Where, $W$ is a matrix and $F$ is the Frobenius Norm.  How can I find the derivative of $\frac{\partial J}{\partial W}$ ?


I've heard of the one found here:    about flipping a coin fourteen times, having it come up heads ten times, and then betting on whether the coin would come up heads on the next two tosses.  Are there others? Are there any really classic problems in this area?

Note: I am aware of  differences between Bayesian and frequentist statistics. For example "what is the probability that the coin on the table is heads" doesn't make sense in frequentist statistics, since it has either already landed heads or tails -- there is nothing probabilistic about it. So the question has no answer in frequentist terms. But such a difference is specifically not the kind of difference I'm asking about. Rather, I would like to know how their predictions for well-formed questions actually differ in the real world, excluding any theoretical/philosophical differences such as the example I mentioned above. So in other words: What's an example of a question, answerable in both frequentist and Bayesian statistics, whose answer is different between the two? (e.g. Perhaps one of them answers "1/2" to a particular question, and the other answers "2/3".) Are there any such differences?  If so, what are some examples?  If not, then when does it actually ever make a difference whether I use Bayesian or frequentist statistics when solving a particular problem? Why would I avoid one in favor of the other?


Quite a few people paste in bit.ly links into comments or answers, sometimes even for linking to other pages (or answers within the same page) on Stack Overflow. This way, you do not see where the link is pointing to.  Assuming that there is an API to do this, should the site automatically rewrite the links to point at the original URL?   Are there any benefits to leave them at bit.ly?   Why are people pasting them through bit.ly in the first place? Stack Overflow displays shortened URL anyway, so formatting should not be a concern.

Related:  |  |    Ban URL shorting services from being used in questions/answers. I have three major reasons to request this:   It's abused to hide LMGTFY-Links (interestingly, this behavior ranges from the 20 rep Newcomer to the 50K User) It's used for inlined links, which negatively affects usability (I can't see where the link is taking me) It's used instead of proper formatting   As requested by ChrisF, a few examples of misuse (all removed by now):          Update as of 19th Aug '13: In the light of the recent , Id' like to suggest to reconsider the stance on this.  Those spam attacks are mostly enabled by the fact that the spammers can hide behind shortened URLs (goo.gl in this case), making blacklisting of the original URL impossible. Banning at least the most well-known services would force spammers to use their original URL (or would block the attack as a whole), making it easier to directly target them.


I have a macbook pro 2010 15 inch A1286. My problem is that the power adapter is plugged into the MacBook but it indicates that the battery is not charging and "Power Source: Power Adapter". The battery cycle count is over 1000 and condition is "replace soon". I was wondering if this problem with my device not charging is due to the degradation of the battery. Thank you for your help and if there is any more information that I should provide to facilitate this diagnostics, please feel free to say so.

I see that the question "why is my MacBook not charging?" gets asked a lot. The problem is, there are multiple reasons. Possible points of failure are: charger, cable, magsafe connector, DC input board, logic board, battery. (Have I missed any?). What is the best sequence for a user to follow, to diagnose the problem? By way of example, here are the first steps that I usually try:  Make sure the charger is working. Either use your charger on a different Mac, or test a spare charger with your Mac.  Check the connection. There might be gunk in your port that's stopping the connector from lying flat.  Try resetting the SMC and PRAM.  If the computer boots, run Coconut Battery to determine battery status.   This is where I get a bit stuck. For example, I have a machine here that boots fine when plugged in, but not from battery. Disconnecting the MagSafe causes the machine to switch off. Sounds like it's a dead battery, except that Coconut reports the battery as detected, in good condition, but not charging. What steps should I take next? Specifically, I'm asking for a generic algorithm to help determine the source of the fault (preferably without swapping out lots of components one by one)?


I want to find the font types and sizes used in a pdf document. I managed to find the font types with strings foo.pdf | grep FontName as described in the link below. Is there a similar trick that will allow me to find the font sizes?

I'm using Foxit Reader as default PDF viewer. How can I see what type of font is used for a selected part of a PDF document?  (If this can only be done with another software, I'd prefer a freeware as I don't want to pay for just viewing selected fonts' types.)


My boss says it is better to use "A guide on travel procedures" as she is refering to procedures. Does that make sense?

The following link includes a guide ___________ how to use it.  How should I fill in the blank, on, for, or about?


Is it possible to load the same csv twice with d3?  I have a flask server which updates a csv file every 10 seconds. I would like to reload the graph of the data every 10 seconds.  I used setInterval and inside I reuse  d3.csv("static/data.csv", function(error, data) {...   But when I print the data variable I always get the same graph, as if the csv didn't change.  When I refresh the page it takes the new data and there is no problem.

It looks like if I load dynamic content using $.get(), the result is cached in browser.  Adding some random string in QueryString seems to solve this issue (I use new Date().toString()), but this feels like a hack.   Is there any other way to achieve this? Or, if unique string is the only way to achieve this, any suggestions other than new Date()?


Code  hostDir = 'https://www.example.com/a/b/' path = '../../script.js' x = hostDir + path import requests print(requests.get(x).content.decode('utf-8'))   When I run above code, it gives following error:   <TITLE>Access Denied</TITLE>
Access Denied
  You don't have permission to access "http&#58;&#47;&#47;www&#46;xyz&#46;com&#47;a&#47;b&#47;&#46;&#46;&#47;&#46;&#46;&#47;script&#46;js" on this server.
 Reference&#32;&#35;18&#46;3da21ab8&#46;1546852663&#46;7da6a685     I can see that this issue is due to path '../../' and '/a/b/' but requests module is not able to convert it to ''  Considering '../../' and '/a/b/' both can be any number of times.  Please help me out to deal with this problem so that it can be converted into ''

Is there a library in python that works like this?  >>> resolvePath("http://www.asite.com/folder/currentpage.html", "anotherpage.html") 'http://www.asite.com/folder/anotherpage.html' >>> resolvePath("http://www.asite.com/folder/currentpage.html", "folder2/anotherpage.html") 'http://www.asite.com/folder/folder2/anotherpage.html' >>> resolvePath("http://www.asite.com/folder/currentpage.html", "/folder3/anotherpage.html") 'http://www.asite.com/folder3/anotherpage.html' >>> resolvePath("http://www.asite.com/folder/currentpage.html", "../finalpage.html") 'http://www.asite.com/finalpage.html'


Talking with a friend of mine about the existence if God, I argued that science is the better way to believe in something, instead of believing in something using personal belief or faith; for example for the existence of God I argued that since science hasn't given a proof of the existence of God there is no reason to believe in it; however my friend said that he believes in God because he "feels him in his heart" and stated that it is a reasonable reason to believe.  My question: is science better than personal belief? And if it is so, why?

In , John Loftus often makes statements like:  Faith, as I argue, is an irrational leap over the probabilities. Probabilities about such a matter are all that matter. We should think exclusively in terms of them. (19) If God created us as reasonable people, then the correct religious faith should have sufficient evidence for it, since that’s what reasonable people require. (22) Because science is the only game in town. It works. It produces the goods. There isn’t a better alternative. (119)  Loftus' attitude seems representative among many atheists; while I'm aware that there are other views, it is this kind of view which leads to the title of this question: Ought we only form beliefs based on sufficient empirical evidence? Here are some sub-questions which may help guide answers:  How can we get an ought from an is, given that evidence only describes what is? Reformulating the title as a hypothetical imperative doesn't seem to help, because the scientific method doesn't seem to ever make a hypothetical imperative binding. And yet, surely those who would agree with the quoted text would find certain hypothetical imperatives binding?  Given that the scientific method includes "basic arithmetical truths and also certain truths about formal provability",  seems to apply: a given axiomatic formulation of the scientific method will be unable to imply certain (virtually all, it turns out) truths. To say that science is complete—there are no other methods of knowing things—seems to imply that science is inconsistent. Is this 'seems' an illusion?  Does the scientific method require that we make observations prior to forming hypotheses? It could be argued that probabilistically, trying to come up with hypotheses before making a 'sufficient' number of observations will result in a failed hypothesis too much of the time. Is there evidence to support this which can probabilistically rule out all other kinds of hypothesis-forming?  Must we accept any unfalsifiable claims? The answer seems to be 'yes', given e.g. the example of crystal structure discussed by Michael Polanyi in  (43-48, 1984 paperback). A set of geometries seemed to well-describe many crystals found in nature, and even if some crystals aren't well-described, that doesn't falsify the instances in which it does. This opens up the question of which unfalsifiable claims we ought to accept.  If we model human reasoning as , we can ask what is meant by 'sufficient' by what the 'probabilities' are, prior to any observations: what  ought we start with? I am tempted to say "the most effective one", but that presupposes a purpose; are we given an objective purpose?   I am left with the suspicion that one ought to only follow the scientific method to the extent that one only wants to predict one's future observations—this smells like a tautology. It seems to beg the question to say that the most important area of 'truth' is objective reality, a question which cannot be answered with the scientific method. A 'yes' answer to the main question would seem to fall prey to something like  of .  I was tempted to phrase my question as:  Is science the only source of truth?  I believe this is a bad question, for a few reasons:  We care about whether a method can reliably arrive at truth/knowledge. The terms 'truth' and 'knowledge' would possibly stir a debate about , which may not be a prerequisite for the answer to my question. My question makes explicit that we are talking about what one ought to do, which is not explicit in the above formulation.


I have a list: A = [6, 4, 3, 5, 2, 1] and I want to create a new list: B = [] where B is populated by the elements from A in range of indices 0 ---> 0 + some variable.   (that is, given a range of indices in A, how can I copy the elements over that range into a new list B?)

I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.


Task: Given n numbers, I store them in a list and find the second highest. I found a solution by acisikta19 on Github:     n = int(input())     arr = list(map(int, input().split()))     arr.sort()     max1=arr[-1]     arr.sort(reverse=True)     for x in arr:         if x!=max1:             result = x             print(result)             break  I wanted to ask what max1=arr[-1] does? Particularly the -1? Second, does arr.sort(reverse=True) simply sort the negative numbers? (The array of numbers is in [-100,100].


Is there anyway to shorten something like this in Javascript: if (x == 1 || x == 2 || x == 3 || x == 4) to something like if (x == (1 || 2 || 3 || 4)) ?

What is the most concise and efficient way to find out if a JavaScript array contains a value? This is the only way I know to do it: function contains(a, obj) {     for (var i = 0; i < a.length; i++) {         if (a[i] === obj) {             return true;         }     }     return false; }  Is there a better and more concise way to accomplish this?


In the exercise, W is a standard, one-dimensional Brownian motion and $0 \lt T \lt \infty$. We are asked to show that  $$\lim_{\beta\rightarrow\infty}\sup_{0\le t\le T}|e^{-\beta t}\int_0^t e^{\beta s}dW_s|=0,\ \ a.s.$$ I know that $E|e^{-\beta t}\int_0^t e^{\beta s}dW_s|^2$ can be calculated, and to deal with "sup", I hope to use BDG inequality or Doob's inequality. However, they can only be applied to (sub or super)martingales. So, I try to do some transformation to the integral. Time-change can make it a Brownian motion as $B_{{1\over2\beta}(e^{2t}-1)}$, and local time gives its decomposition as the sum of a martingale and a increasing process. For the martingale part, I could use Doob's inequality. For the other part, I guess that the increasing process cannot increase as fast as exponential function. I think it may be a way to solve the problem, but I cannot get the estimate about local time.  If you have some idea about this exercise itself, or my problem about the estimation of the local time, please share with me. Thank you!

Let $W_t$ be a one-dimensional Brownian motion and I would like to prove  $$\lim_{\beta\rightarrow+\infty}\sup_{0\leq t\leq T}\left|e^{-\beta t} \int_0^te^{\beta s}\mathrm dW_s\right|=0$$  This is an exercise in Chapter 3 of Karatzas&Shreve, but I don't think this proposition is true since  $$\sup_{0\leq t\leq T}\left|e^{-\beta t} \int_0^te^{\beta s}\mathrm dW_s\right|\geq \left|e^{-\beta T} \int_0^Te^{\beta s}\mathrm dW_s\right|:=|G|$$  where $G$ is a centered Gaussian random variable of variance $(1-e^{-2\beta T})/2\beta$, which implies the precedent proposition can not be true. Could someone tell me where I am wrong or this proposition is not true? Thanks a lot


I need to add a 2000ms delay to the following javascript. How do I do so.  <script type="text/javascript"> $(document).ready(function() {   $("#container_main").hide(); }); $(window).load(function() {   $("#container_main").show(); }); </script>

Is there any JavaScript method similar to the jQuery delay() or wait() (to delay the execution of a script for a specific amount of time)?


i used integer but i am asking for too much big datas. Will memory usage be the same ? Or speed ?  void func1(int *a) {  }  void func2(int &a) {  }    int main() {   int a;     func1(&a); // pointer way   func2(a); // what is it ? is this also pointer way ? }

I know references are syntactic sugar, so code is easier to read and write. But what is the difference between a pointer variable and a reference variable?


Many have said you need a pokemon with a lot of pp-- I'm assuming its because you can't,  but I just legit found a shiny horsea while looking for timid or modest and running away from claunchers.  Do you have to fight or catch all of the pokemon you want to continue the chain? I just want to know how rare this horsea is. Its hasty nature, icyww.

How exactly do I chain fish in Pokemon X and Y? Do i have to talk to the super rod fisherman, or what. I fish every time after the last, but I have no way to know if it is working or not. I run at the end of every battle instead of KO'ing due to limited PP.


I have a table with a checkbox at the start of each row. Each Checkbox has the ID of #tablecheckbox. The table header row has a check icon which should check all boxed in the table. How can I do this with jQuery?

I'd like to do something like this to tick a checkbox using jQuery:  $(".myCheckBox").checked(true);   or  $(".myCheckBox").selected(true);   Does such a thing exist?


i just found out we can defining and instantiate class at once like this  #include <iostream>  using namespace std;  class PLAYERS { public:     int value3;     PLAYERS(int value3)     {         this->value3 = value3;     } }play1(2), play2(3), play3(7);  int main() {     play1.value3 = 2;     PLAYERS play4();     cout << "Hello world!" << endl << play1.value3;     return 0; }   what is it called? when i delete the argument on instantiation of play1, play2, play3 like play4. it will compile error but the play4 is fine. how it can be?

Is there any good reason that an empty set of round brackets (parentheses) isn't valid for calling the default constructor in C++?  MyObject  object;  // ok - default ctor MyObject  object(blah); // ok  MyObject  object();  // error   I seem to type "()" automatically everytime. Is there a good reason this isn't allowed?


I was listening to Eminem's song Stan. I noticed in one verse he says:        But she don't know you like I know you Slim...      At first I didn't believe my ears, but when I read out the lyrics I got astonished. I further searched on Google and found on some other forums that this type of incorrect grammatical usage is either intentional (for some linguistic reasons) or the speaker is uneducated!       So my question is:      What is the purpose of this type of intentional misuse of grammar? How does it appear to native English speakers?      Thank you.

Recently I was exposed to a lot of uses of "She don't + infinitive" ( + don't), instead of "she doesn't + infinitive" ( + doesn't). I'm not sure if it is a mistake or just accepted usage sometimes.   I found it in a very famous songs such as:   "" by Bon Jovi   Also in  (in 3:04)     But she don't know you like I know you Slim, no one does   She don't know what it was like for people like us growin' up, you gotta call me man   I'll be the biggest fan you'll ever lose   Sincerely yours, Stan, P.S. we should be together too   You can find a lot more by searching in you tube "he don't" or "she don't".


I'm trying to design a BLDC motor controller rated to run a 200kW electric motor, 240v dc ~833A. Looking at MOSFETs I've found a TO264 n-channel which is rated for 500V 100A. How are the legs not going to immediately act like fusible links and vaporise?  Edit: I've found a more suited MOSFET [IXFB210N30P3][1] which is 300v 210A Rds of 14.5mOhm continuous power of 1890W.  [  Edit Dos: it appears, in the data sheet, that there is an external lead current limit of 160A and that the chip capability is 210A

I found the  at Digikey.  The datasheet says the device is rated for 400A @ 25C, 1200A @ 25C for 1ms, with a voltage rating of 300V and PD of 1000W.  Really?  This TO-264 package can control 400A of current all day long?  I can short out my TIG welder with it in DC mode?  How do those leads even carry 400A of current?


I read that there are labs that can produces the spikes of the coronavirus. I wonder can they also synthesize ACE2 receptors or parts of them? If yes, can they be used as drugs?

Can ACE2 be produced and used as drug against covid? I read it is the receptor molecule. If it is in the organism the virus should bind to it and could not attack cells anymore? Is that right?


I am trying to upgrade from 19.04 to 19.10 following  instructions. When I come to Select the 3rd Tab called 'Updates', I get the following message:  Unable to download updates: failed to refresh cache: E: The repository 'http://security.ubuntu.com/ubuntu disco-security Release' no longer has a Release file.   How can fix this?

Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc


I have a generic Map which is defined thus  Map<Integer, Book> bookCollection   The Integer is the book ID and the Book is obviously a Book object. The Book object has a member called publicationYear.   How do I sort the Map so that its Book objects are in order by the Book's publicationYear member. So, if I iterate through the sorted map, the oldest book appears first up to the newest book.  At the moment, the Map is randomly sorted.

I am relatively new to Java, and often find that I need to sort a Map<Key, Value> on the values.  Since the values are not unique, I find myself converting the keySet into an array, and sorting that array through array sort with a custom comparator that sorts on the value associated with the key.  Is there an easier way?


For a custom title page I need to set the font size to a specific value not covered by any of the standard \Large etc. font sizes. Therefore, I use the \fontsize command. Reducing to a minimal example my code looks like this:  \documentclass[a4paper,10pt]{article} \begin{document}  {\noindent\fontsize{24pt}{29pt}\selectfont \bfseries This is a\\ long title that is split\\ over multiple lines}  \vspace{2cm} This is normal text. \end{document}   This does change the font size, however it doesn't seem to change the baseline skip resulting in ugly line spacing. See image below:    The following code seems to do the trick  \noindent\parbox{\textwidth}{\fontsize{24pt}{29pt}\selectfont \bfseries This is a\\ long title that is split\\ over multiple lines}   However this seems to be a bit overcomplicated and I don't see why the first code doesn't work. What is the easiest/recommended way to set the font size in my case?

If I type something like this:  {\itshape\LARGE   Dunt venim dolorerosto do odit   ametum vulla conum dolore   conulput in vero od el   Dunt venim dolorerosto do odit   ametum vulla conum dolore   conulput in vero od el }   it results in a block of 4 lines with narrow spacing between the 1st and 2nd line and between the 3rd and 4th line. Line spacing between the 2nd and 3rd line is normal.  I can't fully explaing it to myself so I am looking for a short description for this behaviour. I know for example that with a \par at the end of the text (inside the group), the calculation would correct. But I have no idea why...


I have updated my Ubuntu to 18.04 and facing an UX issue. The new UX has a preview option for grouped windows. For example, when I click Firefox, with multiple open windows, I am getting a preview and I have to select one from this. Given the size of the preview, it is hardly useful, especially when I am coding using the terminal.  I believe the preview on earlier Ubuntu versions is that both windows are shown open bigger side-by-side if I recall properly. Either this or there was no preview and the most recently opened window will open automatically on clicking the Firefox icon and then I can Alt+~ to the other Firefox window. Can someone suggest how to achieve the previous UX as in earlier Ubuntu versions?

I recently installed Ubuntu 18.04 and I'm not keen on the desktop environment. I want the desktop env. I used to have in Ubuntu 14.04. How can I get it?  I've attempted to use , but when I try to install the Unity's 7.2.5 version using the command:  apt install unity=7.2.5   it gives me   E: Version '7.2.5' for 'unity' was not found   For sure I need to add a PPA for this, but which one!?


I do not know my authentication password, that's why I am not able to install anything in my Ubuntu. Where can I find out what is my authentication password or how can I just disable it? Please tell me a solution. I am sick and tired of this authentication password. I have been trying a lot to find out, but I am helples now.

I'm working on a Ubuntu system, and my client has completely forgotten his administrative password. He doesn't even remember entering one; however it is there.  I've tried the suggestions on the website, and I have been unsuccessful in deleting the password so that I can download applets required for running some files. Is there a solution?