I have a regression with 6 independent variables and one of them is highly negatively correlated with one of them. (-0.81 correlation) I was wondering if the regression is still valid or if it's biased? Are the variables still orthogonal? The goal of the regression is inference and all variables are important.

I found a reference in an article that goes like:     According to Tabachnick & Fidell (1996) the independent variables with   a bivariate correlation more than .70 should not be included in   multiple regression analysis.   Problem: I used in a multiple regression design 3 variables correlated >.80, VIF's at about .2 - .3, Tolerance ~ 4- 5. I cannot exclude any of them (important predictors and outcome). When I regressed the outcome on the 2 predictors which correlated at .80, they remained both significant, each predicted important variances, and these same two variables have   the largest part and semipartial correlation coefficients amongst all 10 variables included (5 controls).   Question: Is my model valid despite high correlations? Any references greatly welcomed!    Thank you for the answers!  I did not use Tabachnick and Fidell as a guideline, I found this reference in an article dealing with high collinearity amongst predictors.   So, basically, I have too few cases for the number of predictors in the model (many categorical, dummy coded control variables- age, tenure, gender, etc) - 13 variables for 72 cases. The Condition Index is ~ 29 with all the controls in and ~23 without them (5 variables).   I cannot drop any variable or use factorial analysis to combine them because theoretically they have sense on their own. It is too late to get more data. Since I am conducting the analysis in SPSS perhaps it would be best to find a syntax for ridge regression (although I haven't done this before and interpreting the results would be new to me).   If it matters, when I conducted stepwise regression, the same 2 highly correlated variables remained the single significant predictors of the outcome.  And I still do not understand if the partial correlations which are high for each of these variables matter as an explanation for why I have kept them in the model (in case ridge regression can't be performed).   Would you say the "Regression diagnostic: identifying influential data and sources of collinearity / David A. Belsley, Edwin Kuh and Roy E. Welsch, 1980" would be helpful in understanding multicollinearity? Or might other references be useful?


Solution of matrix equation Ax=b, where $$ A=\left(\begin{matrix} a_1&a_2&\dots&a_n \end{matrix}\right), \ a_i \in \mathbb{R}^n,$$ is not unique, if vectors $$ a_1, \ a_2, \dots, \ a_n $$ are linearly dependent. Then by properties of determinant, $$ \det A=0. $$ However, does it always follow, that if det A = 0, column vectors of A are linearly dependent? Can someone present a proof?

If $A \in M_{n\times n}(F)$ is not invertible then the rank of $A$ is less than $n$, thus $\det(A) =0$.    I proved that way, but looks like too simple so I think maybe there is a trick that I missed. Or I proved it right?   Modification: ($\Rightarrow$) If $A$ is invertible, $AB=I$, $\det(AB)=\det(A)\det(B)=1$ so $\det(A) \neq 0$ ($\Leftarrow$) If $\det(A) \neq 0$ , by Cramer's rule, $Ax=b$ has a unique solution and it means $A$ is invertible ($x=A^{-1}b$)    Now I think I complete the proof.


i have a 3D drawing program which gives me a list of coordinates in a file (.txt or .properties)  the file contains something like that: (almost 5000 lines in it.)  drawCircles(2.03, 5.09, 2); drawCircles(5.02, 6.19, 2); drawCircles(6.12, 2.91, 2); drawCircles(3.12, 1.12, 2); drawCircles(4.37, 8.92, 2); ...   drawCircles is a method for my program which draws ellipses. Everytime i open file and copy all lines into my program and run it.  is there any way for my program to directly read file into program and run it.  Here is my main program to draw circles:  public class DrawClass extends JPanel{ ArrayList<Ellipse2D> arrayCircles = new ArrayList<>(); DrawClass(){     setBounds(0,0,1000,1000);     coordinatesFromFile(); } void coordinatesFromFile(){     //Here is where i paste coordinate from file     //all i want is read file from here and run codes }  void drawCircles(double e1,double e2,double r){     arrayCircles.add(new Ellipse2D.Double(e1, e2, r, r)); }  @Override protected void paintComponent(Graphics g) {     super.paintComponent(g);     Graphics2D g2 = (Graphics2D) g;     g2.setColor(Color.red);     for(int i=0;i<arrayCircles.size();i++){         g2.draw(arrayCircles.get(i));     }      }     }

If I have two variables:  Object obj; String methodName = "getName";   Without knowing the class of obj, how can I call the method identified by methodName on it?  The method being called has no parameters, and a String return value. It's a getter for a Java bean.


Forgive me if this has been asked before (if it has been, I couldn't find it) What punctuation, if any, should I use after "My question is..."? For example,  My question is why is ice so slippery? My question is, why is ice so slippery? My question is: why is ice so slippery?  Which is the correct way to do it? (If it matters, MLA style please)

Possible Duplicate:          Take this statement for example:     That's not the question. The question is what was Colonel Mustard doing in the bedroom with the revolver.   or      That's not the question. The question is what was Colonel Mustard doing in the bedroom with the revolver?    or     That's not the question. The question is "what was Colonel Mustard doing in the bedroom with the revolver?"


A colleague asked me recently about profiling/benchmarking a Java program. Since I am having background in a optimized/compiled programming language, namely Haskell - I was wondering how is it even possible to reliably benchmark jitted programming languages like Java for example?  Wouldn't the just in time compilation interfere and make early samples irrelevant?  And how to know when the JIT has optimized the code "good" enough?

How do you write (and run) a correct micro-benchmark in Java?  I'm looking for some code samples and comments illustrating various things to think about.  Example: Should the benchmark measure time/iteration or iterations/time, and why?  Related:


How can I remove duplicate values from a multi-dimensional array in PHP?  Example array:  Array (     [0] => Array     (         [0] => abc         [1] => def     )      [1] => Array     (         [0] => ghi         [1] => jkl     )      [2] => Array     (         [0] => mno         [1] => pql     )      [3] => Array     (         [0] => abc         [1] => def     )      [4] => Array     (         [0] => ghi         [1] => jkl     )      [5] => Array     (         [0] => mno         [1] => pql     )  )


Problem :   Verify if the statement if true of false -  The set $S$ of all real numbers of the form $\frac{m}{10^n} $ with $m,n \in \mathbb{Z} $ and $n \geq 0$ is dense in $\mathbb{R}$ .  I think this true .  Reason : $S$ is actually a subgroup of $\mathbb{R}$ with respect to addition .  Now i know the theorem that any subgroup of $\mathbb{R}$ is either cyclic or dense .   If $S$ were cyclic then there non-zero $m$ and an $n\geq 0$  such that $\frac{m}{10^n} $ generates $S$ . So there is a non-zero $i\in \mathbb{Z} $ such that $0= \frac{m}{10^n}+..\frac{m}{10^n}$ ( $i$ times adiition )$ = \frac {mi}{10^n} $ which is not possible because neither $m$ or $i$ is $0$ .So $S$ can be cyclic . Hence it is dense .

The set $S$ of real numbers of the form $m/10^n$, $m,n$ integers and $n$ greater than or equal to $0$, is a dense subset of $\mathbb R$ or not??   I know dense means closure of $S$ in $\mathbb R$ is $\mathbb R$ then it will be dense. How to prove or disprove I have no idea.


For $n$ equal to $1$ it's easy:      $(e^x)'=e^x  $   for $n=4$ also:     $\frac{d^4}{dx^4} \sin x = \sin x$   Now is there a way to construct a function where the $n$-th ($\in \mathbb{N}$) derivative is the first derivative which is the function again?  $$\frac{d^n}{dx^n} f_n(x) = f_n(x)$$    Especial looking for big $n$ values. But example functions for (small) $n \neq \{1;4\}$ would also be interesting (write those in comments).

As I attempted to solve for a function that is the $k$-th derivative of itself where $k$ is some natural number, and generalise the result, I realised it gets very hard to prove anything. For $k= 1$, apart from trivial corner cases, it's the exponential function with any constant multiplied.  For $k=2$, along with the exponential function and it's reciprocal, it works for their sum along with any mixture by constants multiplied...  For any $k$, I guessed it should be of the form $e^{x w}$ where w is the $k$-th root of unity. And we can add all these $k$ terms for each root with constants multiplied.  While it is easy to verify it's satisfying the condition, it is beyond my scope to prove this is the only family of functions that satisfy it.  I am hoping for some interesting math at work here, and want to know if this is an already established fact. Also, how do I prove anything here?


How could I draw (stroke) the outline of a 3D object in a cartoon style with GLKit?  I'm referring to something like this:     However we can start with a simple line around the object and then try to improve the stroke with a shader.  I'm drawing the object with this code:  glBindVertexArrayOES(_vertexArray); glDrawElements(GL_TRIANGLES, sizeof(Indices)/sizeof(Indices[0]), GL_UNSIGNED_BYTE, 0)   As I'm not very familial with GLKit: all the solutions I've found make use of OpenGL APIs not supported by OpenGL ES.

How can I draw outlines around 3D models? I'm referring to something like the effects in a recent Pokemon game, which appear to have a single-pixel outline around them:


Wikipedia tells me that      Reference is a simple reference datatype that is less powerful but safer than the pointer type inherited from C   I am learning C++ and I came across the function vector::front().  In the documentation it says the fuction     Returns a reference to the first element in the vector.   However, as shown in the code below, the return value is treated as not the reference but the element itself.  vector<int> my_vector(1); // initialising a vector my_vector.push_back(10); // inserting 10 int number = my_vector.front() + 1; // number = 11   If my_vector.front() is a reference to the first element, shouldn't it be dereferenced with (*) in order to access the value?   Seeing that   *my_vector.begin() == my_vector.front() == 10  and I can do arithmetics to the iterator, should I think of iterators as something similar to pointers in C, and think of reference as a value?

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?


Why do hair continuously grow on human heads, while the same doesn't happen on other parts of the human body? Where there are hair, they only usually grow to a fixed length; but they seem to have no limit (or at least a much higher limit) as long as the head is concerned (and the face, in men).  Why does this only happen on humans? When did it start happening? What kind of evolutionary advantage could there be in overly-long head hair, so that humans have them while other primates and mammals don't?    I know there are various questions around about why humans have much less body hair than other mammals; mine is related but different: why are we the only species with so much hair on our head, to the point that they might even become inconvenient if we don't cut them?

Many people can grow extremely long head hair and facial hair. Are there evolutionary theories as to why this is the case? It seems like having long hair could be a disadvantage, and extremely long hair seems to be rare in other mammals.


The polynomial ring $\mathbb{Q}[x]$ has a basis given by the "binomial powers" $\binom{x}{0}, \binom{x}{1}, \binom{x}{2}, \ldots$ where we define $$ \binom{x}{k} = \frac{1}{k!} x (x - 1) \ldots (x - k + 1).$$ Given $n, m \geq 0$, is there a nice expression for the product of two of these basis elements $\binom{x}{n} \binom{x}{m}$ in terms of the binomial basis?

I am stuck with the following problem. Every polynomial of degree $d$ can be expressed as $$ p(x) = p_d \binom{x}{d}+ p_{d-1}\binom{x}{d-1} + \cdots + p_0 \binom{x}{0} $$     What is the representation of    $$ \binom{x}{i} \binom{x}{j}  $$   in such a basis?   I have no idea how to solve this...


Online I found the following statement that for $X$ an infinite set, if there is a bijection from $X$ to $\mathbb{N}$ this is equivalent to there is an injection from $X$ to $\mathbb{N}$. How would I prove this?  Attempt: The fact that if there is a bijection it is also an injection is true by definition of bijection. Beyond that, I don't know how to demonstrate that an injection is equivalent to a bijection for an infinite set $X$ to $\mathbb{N}$.

Here is the proof I tried to weave while trying to prove this theorem:     Theorem. Every infinite subset of a countable set is countable.      Proof. Let $A$ be a countable set and $E\subset A$ be infinite. Then $A\thicksim\mathbb{N}$. This implies that there is a sequence $\left\{x_{n}\right\}_{n\in\mathbb{N}}$ where $x_{n}\in A$. Construct a sequence $\left\{n_{k}\right\}_{k\in\mathbb{N}}$ where $x_{n_{k}}\in A$, $n_{1}$ is the smallest positive integer such that $x_{n_{1}}\in A$, and $n_{k+1}>n_{k}$. Then      $$ E=\bigcup_{k=1}^{\infty}x_{n_{k}}, $$      and $E$ is countable, because $E\thicksim\mathbb{N}$. $\blacksquare$   Is it convincing?


I am trying to get the rightmost header to be centered with the numbers in its column.  From the MWE below, my table compiles with the rightmost header skewed to the right.  Can you help me center align the rightmost header to the numbers in its column so that it will be consistent with the other three entries of the table?   Here is the code:  \documentclass{book} \usepackage[top=3cm,bottom=3cm,left=3.2cm,right=3.2cm,headsep=10pt,a4paper]{geometry} \usepackage{pgfplotstable, booktabs} \pgfplotsset{compat=newest} \usepackage{longtable} \usepackage{amsmath} \usepackage{array} \usepackage{fancyhdr} \pagestyle{fancy} \fancyhf{}  \usepackage{filecontents} \begin{filecontents}{TABDAT1.txt} c   G(c)GTOT    GhatGTOT    MODELPERFORM 0.994680851 0.067915691 0.067915691 1 0.989361702 0.135831382 0.114754098 0.844827586 0.984042553 0.18735363  0.182669789 0.975 0.978723404 0.234192037 0.201405152 0.86 0.973404255 0.271662763 0.227166276 0.836206897 0.968085106 0.306791569 0.255269321 0.832061069 0.962765957 0.339578454 0.306791569 0.903448276 \end{filecontents}  \begin{document}   %%% Code from Dr. Christian ------ for not using headers.---------------------- \pgfkeysifdefined{/pgfplots/table/output empty row/.@cmd}{     % upcoming releases offer this more convenient option:     \pgfplotstableset{         empty header/.style={           every head row/.style={output empty row},           outfile=pgfplotstable.example1.out.tex,         }     } }{     % versions up to and including 1.5.1 need this:     \pgfplotstableset{         empty header/.style={             typeset cell/.append code={%                 \ifnum\pgfplotstablerow=-1 %                     \pgfkeyssetvalue{/pgfplots/table/@cell content}{}%                 \fi             }         }     } }  \noindent {\scriptsize \pgfplotstabletypeset[col sep=space,empty header, columns={c,G(c)GTOT,GhatGTOT,MODELPERFORM},      % display specified columns begin table=\begin{longtable}, end table=\end{longtable}, columns/c/.style={column type={c},dec sep align,precision=4,fixed,fixed zerofill}, columns/G(c)GTOT/.style={column type={c},dec sep align,precision=4,fixed,fixed zerofill}, columns/GhatGTOT/.style={column type={c},dec sep align,precision=4,fixed,fixed zerofill}, columns/MODELPERFORM/.style={column type={c},dec sep align,precision=4,fixed,fixed zerofill}, every head row/.append style={before row={%     \caption{This is a Table with Data}%     \label{tab:DataTable}\\\toprule     \multicolumn{2}{c}{\emph{c}} & \multicolumn{2}{c}{$\dfrac{G(c)}{G_{TOT}}$} & \multicolumn{2}{c}{$\dfrac{\hat{G}(c)}{G_{TOT}}$} & \multicolumn{2}{c}{$\phi(c)$} \\[7pt] \toprule     \endfirsthead     %     \multicolumn{8}{c}%     {{\bfseries Table \thetable\ Continued from previous page}} \\     \toprule     %     \multicolumn{2}{c}{\emph{c}} & \multicolumn{2}{c}{$\dfrac{G(c)}{G_{TOT}}$} & \multicolumn{2}{c}{$\dfrac{\hat{G}(c)}{G_{TOT}}$} & \multicolumn{2}{c}{$\phi(c)$} \\[7pt] \toprule     \endhead     %     \midrule \multicolumn{8}{r}{{Continued on next page}} \\ \bottomrule     \endfoot     %     \midrule     \multicolumn{8}{r}{{End of Table}} \\ \bottomrule     \endlastfoot     }}, ]{TABDAT1.txt}  \end{document}

I am developing some tables on LaTeX environment and I am having some troubles with the spacing. Originally, I was able to generate the tables using the standard \begin{table}, but then I tried to add some features, as the capability to break the table if it is too long (using longtable) the issue appears. I also want to align numbers by decimal point and center, reason why I use siunitx package. The problem is on the last column, which had a width almost the double than the others. If I specify the column width, the problem "disappear", but I'm really interested in the possibility of automatically generate the width of the table.  The code is the following:  \documentclass[paper=a4, fontsize=11pt]{scrartcl} \usepackage[english]{babel} \usepackage{siunitx} \usepackage{longtable} \usepackage{booktabs}  \begin{document} \begin{longtable}{l*{4}{S}} % no problem specifying the column width\begin{longtable}{l*{4}{S[table-column-width=1.25cm]}} \caption{Univariate Item Descriptives}\\ \toprule \multicolumn{1}{l}{\textbf{Item}} & \multicolumn{1}{c}{\textbf{Mean}} &    \multicolumn{1}{c}{\textbf{Variance}} & \multicolumn{1}{c}{\textbf{Skewness}} & \multicolumn{1}{c}{\textbf{Kurtosis}} \\ \midrule \endfirsthead \multicolumn{5}{c}% {\tablename\ \thetable\ -- \textit{Univariate Item Descriptives (Continued from previous page)}} \\ \toprule \textbf{Item} & \textbf{Mean} & \textbf{Variance} & \textbf{Skewness} & \textbf{Kurtosis} \\ \midrule \endhead \hline \multicolumn{5}{r}{\textit{Continued on next page}} \\ \endfoot \bottomrule \endlastfoot 2. EX +         & 2.788   &    1.060 &        -0.120   &   -0.368\\ 3. DS +         & 4.080   &    0.853 &        -1.141   &    1.379\\ 4. AM +         & 3.684   &    0.705 &        -0.541   &    0.744\\ 5. EX +         & 3.653   &    1.043 &        -0.709   &    0.149\\ 6. DS -         & 2.240   &    1.665 &         0.725   &   -0.603\\ 7. AM +         & 4.292   &    0.876 &        -1.627   &    2.705\\ 8. EX -         & 2.419   &    1.588 &         0.449   &   -0.897\\ 9. AM +         & 3.255   &    0.923 &        -0.234   &   -0.037\\ 10. DS -        & 3.449   &    1.408 &        -0.453   &   -0.599\\ 11. EX +        & 3.678   &    1.232 &        -0.669   &   -0.219\\ 12. AM -        & 2.830   &    1.162 &         0.029   &   -0.565\\ 13. EX -        & 3.452   &    1.205 &        -0.410   &   -0.336\\ 14. DS -        & 2.442   &    1.374 &         0.310   &   -0.893\\ 15. AM -        & 2.114   &    1.168 &         0.729   &   -0.176\\ 16. EX -        & 3.070   &    1.085 &        -0.176   &   -0.347\\ 17. AM +        & 3.893   &    1.116 &        -0.954   &    0.544\\ 18. EX +        & 3.311   &    0.964 &        -0.238   &   -0.066\\ 19. AM -        & 2.674   &    1.404 &         0.245   &   -0.780\\ \end{longtable} \end{document}


How can I put a vertical line | within the \verb command to get something like this

In LaTeX, if I use \verb, how can I escape |? For example, I want to display ab|bc: \verb|ab[]bc|. What should replace []?


After rain, we often find shrimp-like creatures in the puddles left on our concrete patio. We have also found them in the cat's water bowl (on the same patio). They are pink in color, and around 3mm long.   The idea of shrimp on land seems absurd, but that's certainly what they look like.  We live in Okinawa, and even long-time local residents don't seem to know what they are. We're on a cliff 10 meters tall, right next to the beach.  My questions: what are they, and how do they magically appear after rain? From eggs that are lying dormant on my patio, waiting for rain??  The alleged duplicate is quite helpful. My question is slightly different because I live beachside in Okinawa, not in central Florida, and my creatures are much smaller. Probably a related species, though one that doesn't seem to be familiar to the locals.

Our family has 2 cats and a dog.  We keep food and water bowls outside for them.  We clean and refill the water bowls every day.  Almost every morning, the water bowl is teeming with small aquatic insects of some kind, which look and act like little shrimp.  I would guess them to be 5 to 8 mm in length, on average.  What are these, and where are they coming from?  They appear to be aquatic, since they survive and swim in the water for hours -- but how do they get there?  We live in central Florida, USA.


Let's say I cast  (an instant) before my opponent attacks. I choose the "all creatures get -1/-1 until end of turn" and then my opponent attacks with, among other creatures, a  which says "whenever Precinct Captain deals combat damage to a player, put a 1/1 white Soldier creature token onto the battlefield".  If the Precinct Captain successfully deals combat do the 1/1 Soldier tokens it creates die instantly because of the Golgari Charm's "-1/-1 until end of turn" or do they survive because they weren't in play at the time the "-1/-1 until end of turn" took effect?

My opponent casts , which resolves, then he attacks with his creatures.  In my hand, I have a creature card with Flash. If I summon this creature before the declare blockers step, will it be affected by Predatory Rampage's blocking requirement?


I have a checkbox inside jquery datatable which is created dynamically with the code below.  $('#SettingsDatatable').dataTable({ "order": [], "dom": "Bfrtip", "buttons": ["copy", "csv", "excel", "pdf", "print"], "columnDefs": [{    "targets": 0,    "render": function (data, type, full, meta) {    return '<input type="checkbox" ' + (data == 'True' ? 'checked' : '') + ' /> &nbsp;&nbsp;&nbsp;  ';   }}   Now I want to select this checkbox with code below.   $('#SettingsDatatable input[type="checkbox"]').on('click', function (event) {                 alert("Hello in"); });   But its not getting selected.  Update  $('#SettingsDatatable').on('click', 'input[type="checkbox"]', function (event) {       event.preventDefault();      event.stopPropagation();       return false; });

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


Superman gets his powers from the radiation generated by our sun, but once he no longer has access to this radiation, how long do his powers last?  I'd be looking for examples from comics or the animated universe if possible.

If we were to take superman, and hide him from a yellow sun by any means (underground, too far, block the sun, perpetually staying in night regions), how long would it take for his powers to be lost?  I'm not looking for speculation, I am asking for comic or cartoon examples, hopefully with a given time frame. Considering the average day has between 8 to 16 hours of light, he can obviously recharge in at least that amount of time.  Of course, no red sun/lights/lamps involved, that's cheating.


i have a gridview that get data from an sqlite database and i want to delete a row by onItemLongClick but i get a error i cannot solve it  @Override public boolean onItemLongClick(AdapterView<?> parent, View view,                                int position, long id) {     dataBase.delete(mDBHelper.TABLE_LIENS, mDBHelper.toString()                                            + "="                                            + mLienList.get(position), null);      mLienList.remove(position);     adapter.notifyDataSetChanged();     Toast.makeText(Main2ActivityAdmin.this, "Lien supprimer", Toast.LENGTH_LONG).show();      return true; }   stack trace is:  E/AndroidRuntime: FATAL EXCEPTION: main Process: PID: 21230 java.lang.NullPointerException: Attempt to invoke virtual method 'int android.database.sqlite.SQLiteDatabase.delete(java.lang.String, java.lang.String, java.lang.String[])' on a null object reference

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?


Suppose that the power series $$\sum_{n=0}^\infty a_nz^n$$ has a radius of convergence of $R\in (0,\infty)$. How can we find the radius of convergence of $$\sum_{n=0}^\infty a_nz^{n^2}$$

I've got a start on the question I've written below. I'm hoping for some help to finish it off.     Suppose that the power series $\sum_{n=0}^{\infty}c_n x^n$ has a radius of convergence $R \in (0, \infty)$. Find the radii of convergence of the power series $\sum_{n=0}^{\infty}c_n x^{2n}$ and $\sum_{n=0}^{\infty}c_n x^{n^2}$.   From Hadamard's Theorem I know that the radius of convergence for $\sum_{n=0}^{\infty}c_n x^n$ is $R=\frac{1}{\alpha}$, where  $$\alpha = \limsup_{n \to \infty} |a_n|^{\frac{1}{n}}.$$  Now, applying the Root Test to $\sum_{n=0}^{\infty}c_n x^{2n}$ gives  $$\limsup |a_nx^{2n}|^{\frac{1}{n}}=x^2 \cdot \limsup |a_n|^{\frac{1}{n}}=x^2 \alpha$$  which gives a radius of convergence $R_1 = \frac{1}{\sqrt{\alpha}}$. Now for the second power series. My first thought was to take  $$\limsup |a_nx^{n^2}|^{\frac{1}{n^2}}=|x| \cdot \limsup |a_n|^{\frac{1}{n^2}}$$  but then I'm stuck. I was trying to write the radius of convergence once again in terms of $\alpha$. Any input appreciated and thanks a bunch.


I would like to know if the live image of a Installation disk can be used to recover the system or Grub?

I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back?


The above equation appears without proof on page 9 (equation 3) of Andrew Ng's notes on   I have tried various approaches to prove this to no avail. From the notes it seems that it should be provable from first principles. I tried using the ordinary chain rule on an element by element basis, but this quickly gets unwieldy. Any hint on the approach to resolve this would help a lot.

How is the derivative of $\mbox{Trace}\left\{ X^T A X B\right\}$ with respect to matrix $X$ equal to $AXB + A^TXB^T$?  \begin{align}   \nabla_X \ \textrm{Trace}\left\{ X^T A X B\right\} = AXB + A^TXB^T \end{align}  where $A$ and $B$ matrices are given.


I have two ways we can iterate through each entry in hashmap, can you explain which one is to be preferred over other and why ?  HashMap m = new HashMap(); m.put("A",100); m.put("B",100); m.put("C",100); m.put("D",100);   One way to iterate  Set s1 = m.entrySet(); Iterator itr = s1.iterate(); while(itr.hasNext()) { Map.Entry m1 = (Map.Entry)s1.next(); System.out.println(m1.getKey()+"..."+m1.getValue); }   Second Way to iterate  Set<Map.Entry<String,Integer>> s1 = m.entrySet(); for(Map.Entry<String,Integer> m1:s1){ System.out.println(m1.getKey()+"..."+m1.getValue);  }

If I have an object implementing the Map interface in Java and I wish to iterate over every pair contained within it,  what is the most efficient way of going through the map?  Will the ordering of elements depend on the specific map implementation that I have for the interface?


I want to mention a Perl variable name within a TeX file for PDF-ing (via pdflatex). Masking the dollar sign malfunctions with:    log-file:    ! Missing $ inserted.    <inserted text>                  $    l.7    \item \textit{\$fmt_line_req}                                     , d.i. eine den User-W\"unschen angepa\s...    I've inserted a begin-math/end-math symbol since I think    you left one out. Proceed, with fingers crossed.  The MWE:   \documentclass[a4paper,10pt]{article}   \usepackage[utf8]{inputenc}        \begin{document}      %\begin{enumerate}   %   \item \textit{\$fmt_line_req}, d.i. eine den User-W\"unschen angepa\ss{}te Formatzeile   %   \item \textit{\$head_line_req}, d.i. die Spaltenk\"opfe wunschgem\"a\ss{}   %   \item \textit{\$content_req}, d.i. die Tabellenzeilen mit w.o. gew\"unschter Spaltenpositionierung   %\end{enumerate}      \begin{enumerate}      \item \textit{[\%spaltenformatierung\%]}, d.i. eine den User-W\"unschen angepa\ss{}te Formatzeile      \item \textit{[\%spaltenueberschriften\%]}, d.i. die Spaltenk\"opfe wunschgem\"a\ss{}      \item \textit{[\%content\%]}, d.i. die Tabellenzeilen mit w.o. gew\"unschter Spaltenpositionierung   \end{enumerate}      \end{document}     The masking of % is ok! So, is there a solution to get the dollar sign in this environment? The following output is only possible if dollar sign lines are commented. The \textit format is what I want. But I need itemize/enumerate lines with the dollar sign in same manner.   [%spaltenformatierung%], d.i. eine den User-Wunschen angepate Formatzeile  [%spaltenueberschriften%], d.i. die Spaltenkopfe wunschgema  [%content%], d.i. die Tabellenzeilen mit w.o. gewunschter Spaltenpositionierung

I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out?


I have a directory containing a file that I want to delete. However, the name of the file is too long:  > Remove-Item -Recurse target Remove-Item : The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters.   I cannot delete it with shift+delete in Windows Explorer either:    I cannot move the file either, since its name is too long. Is there any way I can delete the file? I use Windows 8.1. Bonus points if you can explain how such a file could end up on my drive in the first place, and why Explorer and PowerShell can't delete it.

Windows seems to have a length limit on file names when trying to delete, though it won't prevent those files from being created.  Our build process creates a number of temporary files (many build off of a WSDL) that run afoul of this limit.  Our ant script is somehow able to delete them when doing a clean, but sometimes I need to delete the workarea directory (where all the temp files go) without actually doing a full clean from ant.  This is the same errors , but the answers there don't really work for me as I'm dealing with a directory, not a file, and I don't always know what specific files or subdirectories are causing the problem.  And I'm trying to avoid any manual process (other than triggering a single command) to actually delete them.  If I try deleting the directory from Explorer I get the error   Cannot delete [file name]: The file name you specified is not valid or too long.   Specify a different file name   Trying Remove-Item in powershell gives the following error:  Remove-Item : The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters. At line:1 char:12 + Remove-Item  <<<< -force -Recurse <directory>   Does anyone know of any tools or easy ways to get around this delete error without having to manually find the problem files and move/rename them?


Even after changing the language for a login from Arabic to us_english it doesn't save it. It continues to show Arabic. The server default language is us_english. How do I fix this. Thanks !

I have just done a clean install of SQL Server 2017 (CU15) on two of my servers, and have noticed that the displayed language for all my logins shows ARABIC instead of '' or 'English'.  Here is the server settings    Here is a login setting    When I run the following SQL code, I get 'us_english' for the default_language_name:  SELECT type_desc,         default_database_name,         default_language_name, FROM master.sys.server_principals WHERE name = 'Cerberus'  | type_desc        | default_database_name    | default_language_name | +------------------+--------------------------+-----------------------+ | WINDOWS_LOGIN    | master                   | us_english            |   Did I mess something up on installation?  How do I correct this?


When $N = 1$, $2^N + 1 = 3$ which is divisible by $3$.  When $N = 7$, $2^N + 1 = 129$ which is also divisible by $3$.  But when $N = 2$, $2^N + 1 = 5$ which is not divisible by $3$.  A quick lookout can determine that when $N$ is an odd number, $2^N + 1$ is divisible by $3$. If is that correct, how can it be proven? Otherwise, what is the counterexample and the correct $N$?  Can this be made into a more general form, for example $2^N + C$ or something similar?

Prove $2^k+1$ divisible by 3 iff $k$ is odd number.  Since I need to prove both direction looks like if I need to prove it's divisible by 3 it's by induction and the other side by congruence..am I right? is there a better wat than induction? and we I still can't prove both direction... any hints?


I can show that $(-1/2 + i\sqrt{3}/2)^3 = 1$. But why does this tell us that $(-1/2 - i\sqrt{3}/2)^3 = 1$? We have only covered what a complex number is, and what a conjugate is in my math class, and we haven't gone beyond that, so no more advanced tools please.

If an polynomial has a complex root, is it necessary that the conjugate of that root is also a root of the polynomial? I am not sure about this. Please comment on this.


First of all, dear , please don't take it as a personal...  Today, I just looked up the  and I saw this user made 543 edits in 24 hours. When I look at , his edits only include (I look at all revisions on last 27 pages) this:   add  tag which questions have already  tag.   Looks like all the edits he made are like this. Since his reputation is over 3k, the system does allow this kind of minor editing without any approval. (As we all know, under 2k reputation users need 3 approval for editing).  Does our system need to prevent this number of minor edits?   Or it is okay for everybody since the user has over 3k reputation?

I was on the Suggested Edit's review tab today, and noticed that this user (take a look at today's ), was putting in hundreds of edits adding the C# tag to questions that didn't really need it. He got over 275 reputation today.   To me, this looked like spamming the edit system to get reputation. I started rejecting them as too minor, with also a custom message telling him this.   Here's one example:  Another:  Another:    And about 20-30 more. I hit my review cap for the day.  Is this valid editing behavior, and, if not, would a mod please get involved?  UPDATE: I've seen a couple of other meta questions about this in the last day, but it looks like the spike in gaming the system is passed.


I just realized that the difference between $n^2$ and $(n+1)^2$ is exactly the $n$th odd number. For example: $5^2 - 4^2 = 9$, the 5th odd number. Is there a proof of this that I can study? This is just my nephew and I playing with series and simple programming problems.

I know that I should use the definition of an odd integer ($2k+1$), but that's about it.  Thanks in advance!


I learned in my physics class that there is a phase shift when light reflects off a low $n$ from a higher $n$, but never got the explanation.

Can anyone please provide an intuitive explanation of why phase shift of 180 degrees occurs in the Electric Field of a EM wave, when reflected from an optically denser medium?  I tried searching for it but everywhere the result is just used.The reason behind it is never specified.


Here are the steps I done:   Opened PNG (not transparent) Selected white areas that I want to make transparent. Layers > Transparency > Add Alpha Channel Deleted selected areas (I see transparency in GIMP) Saved as .xcf file. Exported as PNG (tried various format settings) Reopen PNG in Gimp or other software --> Background is always white, no transparency. Added a transparent layer behind my main image. Re-exported as PNG. (Optionally) tried changing "Lock alpha channel" on both layers. Reopened PNG in Gimp or other software --> Background is now always black, no transparency.   How do I actually export a PNG with transparency from Gimp ?

I’ve had this happen with more than one image lately.   I open an image in GIMP with the purpose of making the background transparent. The first thing I do is Add Alpha Channel. I proceed to remove the background. Once I’m done with that, I export as PNG. But the background isn’t transparent. I can’t figure out for the life of me why that is. I’ve never had this problem before. The image is in RGB mode. I’m using GIMP 2.8.10. Is there some obvious step I’m missing?


So I've been working on my largest project yet, and I've found that a lot of my objects have fields that can be null. Because of this, I'm having to do something like this for every single instance:  if(box1 != null)      box1.draw();   This doesn't seem too bad, but when you have to do that like 8 times, it makes the code seem cluttered. I feel like there could be a simpler way to do this.

I use object != null a lot to avoid . What is an alternative to: if (someobject != null) {     someobject.doCalc(); }


I know this is a very basic question in C, so I apologize beforehand if this is naive: I'm just learning the basics a few days in.  int main() {      // initialize the variables     int num_whitespaces, num_other;     int num_digits[10];     printf("%lu", sizeof(num_digits));  }   This prints 40, which seems odd to me. Why wouldn't this print 10, which would be the length of the array in javascript or so.

How do I determine the size of my array in C?   That is, the number of elements the array can hold?


For my mom's birthday we had a photoshoot with the grandchildren. The photo we would like to print on a canvas is 3530 x 2353 and the desired size is 140 cm x 93.3 cm. Now the software says that the DPI is too low. Can somebody please help?  Is there a way to change the DPI or is the quality of the photo just too low for the size? That would be a pity, because we payed a lot for these professional photographs.  Greetings,  Silke

I would like to create a 60 inch x 20 inch canvas print using an image with a resolution of 4759x1798 (240 pixels per inch) and I would like to know if the image quality will still be good at that size.  To generalise the question, what is the recommended maximum size of an enlargement at varying image resolutions?  e.g. 3 megapixel, 5 megapixel, 8 megapixel, etc


public void DisplayValue<T>(T field, string fieldname)   What does T stands for in above code?  Whats the benefit to do so?  Where we can use this?

I have a VB background and I'm converting to C# for my new job.  I'm also trying to get better at .NET in general.  I've seen the keyword "T" used a lot in samples people post.  What does the "T" mean in C#?  For example:  public class SomeBase<T> where T : SomeBase<T>, new()   What does T do? Why would I want to use it?


Question: From a physiological point of view, when sex is  in a human fetus, is it equally likely to be male or female?  Studies in this area typically measure age at birth, where the data would have already been biased.  There's a slight imbalance in the , in that there's an overall tendency towards males.  However, this could be accounted for in numerous ways, such as abortion.   suggests there would be an evolutionary tendency towards 50:50 chance.

For every 104 male babies, we have 100 female babies and there are statistics which are more reliable. (Those tell us that we have 997 female infants born per 1000 male infants born.) What is the reason for that? Why do we have more male babies than female babies?


i have source code like this public class Solution {       private static List<Integer[]> twoSum(int[] numbers, int targets) {          Map<Integer, Integer> arrayMap = new HashMap<>();             List<Integer[]> pairList = new ArrayList<>();                          for (int i = 0; i < numbers.length; i++) {                 if (arrayMap.containsKey(targets - numbers[i])) {                     Integer[] temp = { arrayMap.get(targets - numbers[i]), i }; // Put the previous and current index                     pairList.add(temp);                 }                 else arrayMap.put(numbers[i], i);             }             return pairList;         }      public static void main(String[] args) {             // TODO Auto-generated method stub             int[]nums = {2, 7, 2, 11, 15};              int target=9;             System.out.println(Arrays.toString(nums));             List<Integer[]> index =twoSum(nums, target);             System.out.println(index.toString());                      } }  but i want to run i got error like this [[Ljava.lang.Integer;@26f0a63f]  how to fix my problem ?

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob]


Suppose that $ a,b,c,d \in \mathbb{R}$,  $a,b,c,d \gt 0$ and  $ c^2 +d^2=(a^2 +b^2)^3$. Prove that  $$ \frac{a^3}{c} + \frac{b^3}{d} \ge 1.$$   If I rewrite the inequation like $ \frac{a^3}{c} + \frac{b^3}{d} \ge \frac{c^2 +d^2}{(a^2 +b^2)^3}$ and manage to simplfy  it brings me nowhere. I try with  Cauchy-Schwarz Inequality but still can not solve it. Plese help

a,b,c,d $\in \mathbb{R}$  $a,b,c,d \gt 0$ and  $ c^2 +d^2=(a^2 +b^2)^3$ prove that  $$ \frac{a^3}{c} + \frac{b^3}{d} \ge 1$$  If I rewrite the inequation like $ \frac{a^3}{c} + \frac{b^3}{d} \ge \frac{c^2 +d^2}{(a^2 +b^2)^3}$ and manage to simplfy  it brings me nowhere. I try with  Cauchy-Schwarz Inequality but still can not solve it. I would very much appreciate it if anyone could help me


I'm writing a script that needs to look up some a value in a CSV file. The CSV file is from an external resource and I don't have much control about the file. So basically, I need to work with the CSV file that is presented to me and I need to deal with that.  Now when I read the CSV file (containing 30.000 rows at the moment), the script crashes at a certain point. It returns this error:  File "C:\Python34\lib\encodings\cp437.py", line 19, in encode   return codecs.charmap_encode(input,self.errors,encoding_map)[0] UnicodeEncodeError: 'charmap' codec can't encode character '\u0161' in position 55: character maps to <undefined>   My python code for reading the CSV file:  import csv with open('mybigfile.csv') as f:     reader = csv.reader(f, delimiter=';')         for row in reader:             print(row)   How would I be able to fix this so it can handle the encoding of the file.

When I try to print a Unicode string in a Windows console, I get an error . UnicodeEncodeError: 'charmap' codec can't encode character .... I assume this is because the Windows console does not accept Unicode-only characters. What's the best way around this? Is there any way I can make Python automatically print a ? instead of failing in this situation? Edit:  I'm using Python 2.5.  Note: @LasseV.Karlsen answer with the checkmark is sort of outdated (from 2008). Please use the solutions/answers/suggestions below with care!!  is more relevant as of today (6 Jan 2016).


Everyone knows the rule (not universally followed) that when a word ends with the letter S, we just add an apostrophe right after the word, instead of adding an apostrophe and an S after it. So, according to the above rule of thumb, it's  Mary's book Johns' wife Mike's pencil Copernicus' theory  The noun itself is pronounced fully with an S at the end, and then the S sound is pronounced immediately. But there's another category of words that end with an S - i.e. most plurals. In this case, at least in writing, we (again, not universally) follow the same rule:  April Fools' Day Mathematicians' paradise Parents' house  But I have noted that in the second case, the missing S after the apostrophe is not pronounced at all, even in formal speech. Is this normal?

Many questions already ask about this topic ( , , etc.) and their answers vary, but they always give exceptions to the apostrophe-s rule, for example:      6.24 The general rule for the possessive of nouns covers most proper nouns, including most names ending in sibilants."   Examples they give include Kansas’s, Ross’s land, and Jones’s reputation. Exceptions include Jesus’  and Moses’.  Which names does this apply to?  Is the Aeneas’  form correct, or is it Aeneas’s instead?


Given that $X$ and $Y$ are random variables drawn from a uniform distribution between $0$ to $1$, i.e. $$ X \sim Uniform(0, 1) \\ Y \sim Uniform(0, 1)$$ And given that $Y \neq 0$, what do we know about $\frac{X}{Y}$? What is it's distribution, PDF, mean, and variance?

Supppse $X$ and $Y$ are standard uniformly distributed in $[0, 1]$, and they are independent, what is the PDF of $Z = Y / X$?   The answer from some probability theory textbook is  $$ f_Z(z) =  \begin{cases} 1/2, & \text{if } 0 \le z \le 1 \\ 1/(2z^2), & \text{if } z > 1 \\  0, & \text{otherwise}. \end{cases} $$  I am wondering, by symmetry, shouldn't $f_Z(1/2) = f_Z(2)$? This is not the case according to the PDF above.


Do you know how to get an asymptotic expansion up to $o(1)$ when $n\longrightarrow +\infty$ for $(u_n)_{n\in\mathbb{N}}$ defined by $u_0>1$ and $\forall n\in\mathbb{N},\; u_{n+1}=u_n+\ln(u_n)$ ? Thank you. Edit : if the problem was easier, I would like to find an equivalent for $v_{n+1}=v_n\times\ln(v_n)$.

Let $f_0=2$ and $f_n=f_{n-1}+\ln(f_{n-1})$. What is a good asymptotic to the sequence $f_n$? With good I mean much better than $f_n \sim \dfrac{3n \ln(2)\ln(n)}{2}$.


I am doing some reverse engineering and want to know which APIs are called from the executable.  I am mostly interested in the APIs called on a particular Windows system DLL.  I guess one way to do that is to get all APIs exposed from the DLL using dumpbin and put breakpoints on all those from Windbg.  Any other approach? This seems like lot of time if I need to monitor many system DLLs.  BTW, I am working on Windows XP and want to monitor one executable which calls some Windows system DLL functions.

Does anyone know tools like  to hook processes? The features I would like to have are:   log function calls on other processes GUI scriptable opensource   I already looked at some tools like:        but none really fully satisfies me.


I'm having some trouble with a smoke simulation... I used quick smoke to simulate a candle and it viewed fine in the 3D view, but when I tried to render it, it showed up invisible.  Example images:  Solid view mode viewport:   Rendered view mode viewport:   Rendered via Camera:   Smoke Domain Material node setup:   Please note that I'm using the 'Quick Smoke' option, not manually creating my smoke.  Thanks, Flae.

I am trying to add smoke to a cigarette. I've created a Cylinder, hit space and chose quick smoke while this sphere was selected. It created a transparent bigger sphere and it is emitting smoke in solid and texture mode. But when I try it out in render mode, it won't show the smoke for some reason. Here is my setup:    The cylinder has a basic white material. Thanks!


The conductors of  claim that causality is broken or at least made fuzzy by quantum mechanics.  Is this really the case?

I'm not sure if this is the right place to ask this question. I realise that this maybe a borderline philosophical question at this point in time, therefore feel free to close this question if you think that this is a duplicate or inappropriate for this forum. Anyway, I'm an electrical engineer and I have some basic knowledge of quantum mechanics. I know that Schrödinger's equation is deterministic. However, quantum mechanics is much deeper than that and I would like to learn more. If this question is not clearly answerable at this point than can anyone point out some recognized sources that try to answer this question. I would appreciate it if the source is scientific and more specifically, is related to quantum theory.


How to find    $$\lim_{x\to 0}\frac{\sin\tan x-\tan\sin x}{7x^7}?$$   L’Hopital rule does not work because derivative of numerator goes very wide and I need to take 7? Can somebody show me other way of finding it?

Find the limit $$\lim_{x\to 0^{+}}\dfrac{\sin{(\tan{x})}-\tan{(\sin{x})}}{x^7}$$  My attempt: Since $$\sin{x}=x-\dfrac{1}{3!}x^3+\dfrac{1}{5!}x^5-\dfrac{1}{7!}x^7+o(x^7)$$ $$\tan{x}=x+\dfrac{1}{3}x^3+\dfrac{2}{15}x^5+\dfrac{1}{63}x^7+o(x^3)$$ So $$\sin{(\tan{x})}=\tan{x}-\dfrac{1}{3!}(\tan{x})^3+\dfrac{1}{5!}(\tan{x})^5-\dfrac{1}{7!}(\tan{x})^7+o(x^7)$$ Though this method might solve, I think this problem has nicer methods. Thanks.


When you are doing an integration by substitution you do the following working. $$\begin{align*} u&=f(x)\\ \Rightarrow\frac{du}{dx}&=f^{\prime}(x)\\ \Rightarrow du&=f^{\prime}(x)dx&(1)\\ \Rightarrow dx&=\frac{du}{f^{\prime}(x)}\\ \end{align*}$$     My question is: what on earth is going on at line $(1)$?!?   This has been bugging me for, like, forever! You see, when I was taught this in my undergrad I was told something along the lines of the following:  You just treat $\frac{du}{dx}$ like a fraction. Similarly, when you are doing the chain rule $\frac{dy}{dx}=\frac{dy}{dv}\times\frac{dv}{dx}$ you "cancel" the $dv$ terms. They are just like fractions. However, never, ever say this to a pure mathematician.  Now, I am a pure mathematician. And quite frankly I don't care if people think of these as fractions or not. I know that they are not fractions (but rather is the limit of the difference fractions as the difference tends to zero). But I figure I should start caring now...So, more precisely,     $\frac{du}{dx}$ has a meaning, but so far as I know $du$ and $dx$ do not have a meaning. Therefore, why can we treat $\frac{du}{dx}$ as a fraction when we are doing integration by substitution? What is actually going on at line $(1)$?

In integrals, we often make 'u' substitutions, which involve writing $u=f(x)$, and then also writing $du=f'(x)dx$. How valid is this? I've heard that you aren't allowed to do things like 'break' up derivatives like they do to solve first order differential equations. So can you do this with integrals, or is it also a mnemonic?


So I have a clean Ubuntu 64bit 12.04 VM ... please explain why the installation fails following simple instructions on the Ubuntu site? (). As a former C# developer I would like to show my colleagues how easy this stuff is, but it just does not seem mature enough if you need to perform contortions to install the SDK. Or am I doing something wrong?  For those interested the issues I get are ones of unmet dependencies because of conflicting version of a library (see below). But to be honest I am more frustrated that the development environment does not work out of the bag, like the python or Microsoft development environments.  sudo apt-get install  qtdeclarative5-ubuntu-ui-toolkit-plugin Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies. qtdeclarative5-ubuntu-ui-toolkit-plugin : Depends:  qtdeclarative5-unity-action-plugin (>= 1.1.0)  but 1.0.0bzr25precise0 is to be installed E: Unable to correct problems, you have held broken packages.   Update: I have already been through all the similar questions in this site and none of them address this issue. I have tried even the detailed ones like this:   I am trying this on a clean 12.04 LTS 64bit VM, so there should be no conflicts.

Occasionally, when I'm installing stuff, I get an error like the following:  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  package1 : Depends: package2 (>= 1.8) but 1.7.5-1ubuntu1 is to be installed E: Unable to correct problems, you have held broken packages.   How can I resolve this?


On the  if you click on the number of votes it will show you the breakdown of up and down votes in the same way that question up and down votes can be viewed.  But if the candidate has more than 100 down votes then the down votes count is missing the minus sign:

There are  2 moderators who have a total vote count of less than 0 during the primary phase. But the total vote count sticks at -1 and is no lower than that. Neal, for example, currently stands at +97/-140 which should give a total vote count of -43.  I remember having seen this during the last elections as well, but I assumed it to be just a bug and I didn't find it important enough to report on meta. But right now, after many elections using the same engine, not only on Stack Overflow, this issue seem still to manifest.  Can we please fix it? Or is this working as designed?


I have 3 classes, Main, Contacts, and ContactsManager. I'm getting the following error in my "searchContact" method. I don't know how to fix. I am looping through the array of contact indexes for as many contacts represented by the "friendsCount variable. Please help me fix the searchContact method. Thank you.  ContactsManager class  public class ContactsManager {      // Fields     Contact [] myFriends;     int friendsCount;      // Constructor     ContactsManager() {         this.friendsCount = 0;         this.myFriends = new Contact[500];     }      // Methods     void addContact(Contact contact) {         myFriends[friendsCount] = contact;         friendsCount++;     }      Contact searchContact(String searchName) {         for(int i = 0; i < friendsCount; i++) {             if(myFriends[i].name.equals((searchName))) {                 return myFriends[i];             }         }         return  null;     } }   Contacts class  public class Contact {      String name;     String email;     String phoneNumber;  }   Main class  public class Main {      public static void main(String[] args) {         ContactsManager myContactManager = new ContactsManager();          Contact con1 = new Contact();         con1.name = "Albert";         con1.phoneNumber = "9545899977";          myContactManager.addContact(con1);          Contact con2 = new Contact();         con1.name = "Jason";         con1.phoneNumber = "9545899944";          Contact con3 = new Contact();         con1.name = "Larry";         con1.phoneNumber = "9545899911";          Contact con4 = new Contact();         con1.name = "Mary";         con1.phoneNumber = "9545899933";          Contact con5 = new Contact();         con1.name = "Saraht";         con1.phoneNumber = "9545899900";          myContactManager.addContact(con2);         myContactManager.addContact(con3);         myContactManager.addContact(con4);         myContactManager.addContact(con5);          System.out.println(myContactManager.searchContact("Jason"));     } }

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?


How do I integrate      $$\int_{-\pi/4}^{\pi/4} (\cos{t} + \sqrt{1 + t^2}\cos^3{(t)}\sin^3{(t)})\;\mathrm{d}t$$   There's no substitution that immediately jumps out at me.

Evaluate: $$\int_{-\pi/4}^{\pi/4}(\cos(t)+\sqrt{1+t^2}\cos(t)^3\sin(t)^3)dt$$  I have tried substituting $t=\tan(\theta)$ and breaking up the $\cos(t)^3$ using $\cos(t)^2=1-\sin(t)^2$, but I can't figure it out.  This question is #21 from the Math subject GRE form GR1268.


C++ newbie here.  Is there a way to call an overloaded function in a base class from the same function name with the same signature in a derived class?  In Smalltalk, I can do it the "super" keyword.  Is there any C++ equivalent?  class MyBaseClass {   void initialize() { doSomething(); } };  class MyDerivedClass : public MyBaseClass {   void initialize() {       super initialize(); // first, call MyBaseClass::initialize()       doLocalInitialize(); // now initialize non-inherited members }   Thanks, Norm

How do I call the parent function from a derived class using C++? For example, I have a class called parent, and a class called child which is derived from parent. Within  each class there is a print function.  In the definition of the child's print function I would like to make a call to the parents print function.  How would I go about doing this?


Below is an excerpt from Gnu sed's documentation at   i text insert text before a line. This is a GNU extension to the standard i command - see below for details.  i\ text Immediately output the lines of text which follow this command.   The wording of these two syntaxes is quite different. In the past, I thought they have the exact same behavior and it's just the syntax is different. I did a bunch of experiment and all tests give the same result. I want to confirm, are there any differences between these two syntaxes? Thanks in advance.

While appending some text after a matched pattern, I wanted to add an empty line with a comment to isolate my additions from the rest. However, I have noticed that for the very first \n, I need to escape the \ with an additional \ (makes it \\n) but this is apparently not required for rest of the appended text. Why is this so?  An example that I produced on a SUSE 11 server (bash v3.2.57(2) and GNU sed version 4.1.5) is:  edwdev@hdpedge1:/edw> sed '/test/a \\nNot a test\nJust Playing' <<< test test  Not a test Just Playing   If I do not escape the first \n (right after the a sed command, I get an n printed instead of a newline.  edwdev@hdpedge1:/edw> sed '/test/a \nNot a test\nJust Playing' <<< test test nNot a test Just Playing   Notice that I have intentionally added a space after a command so that it doesn't conflict accidentally with alternate syntax.  Same behavior is observed if I replace \n with \t.Number of spaces after a command do not seem to matter; the first backslash needs to be escaped to print the special character even after multiple spaces.    Same is the case on another environment, where I originally observed this; a Centos 7 x64 VM, bash version is 4.2.46(2) and sed version is GNU sed 4.2.2  sed -i '/\[mysqld\]/a \\n# <<INSERTED MANUALLY>>\ntransaction-isolation=READ-COMMITTED\ninnodb_flush_method=O_DIRECT\nmax_connections=550\n# <<END OF MANUAL INSERTIONS >>\n' /etc/my.cnf   Output:  ... [mysqld]  # <<INSERTED MANUALLY>> transaction-isolation=READ-COMMITTED innodb_flush_method=O_DIRECT max_connections=550 # <<END OF MANUAL INSERTIONS >>  ...   Output Without Escaping first \n:  [mysqld] n# <<INSERTED MANUALLY>> transaction-isolation=READ-COMMITTED innodb_flush_method=O_DIRECT max_connections=550 # <<END OF MANUAL INSERTIONS >>   Is there any particular reason for this behavior? I am unable to find any details while skimming through the docs (), through, admittedly, I haven't read the entire documentation thoroughly.


I know what it means for a file to have suid permission. It means when other users have execute permission for it, they execute as the owner of the file. But what does it imply when a folder has suid permission? I did some testing and it seems nothing special for the folder. Could anyone help to plain a little? Thanks.  I'm using Oracle Linux 7.6.  root:[~]# cat /etc/*release* Oracle Linux Server release 7.6 NAME="Oracle Linux Server" VERSION="7.6" ID="ol" VARIANT="Server" VARIANT_ID="server" VERSION_ID="7.6" PRETTY_NAME="Oracle Linux Server 7.6" ANSI_COLOR="0;31" CPE_NAME="cpe:/o:oracle:linux:7:6:server" HOME_URL="https://linux.oracle.com/" BUG_REPORT_URL="https://bugzilla.oracle.com/"  ORACLE_BUGZILLA_PRODUCT="Oracle Linux 7" ORACLE_BUGZILLA_PRODUCT_VERSION=7.6 ORACLE_SUPPORT_PRODUCT="Oracle Linux" ORACLE_SUPPORT_PRODUCT_VERSION=7.6 Red Hat Enterprise Linux Server release 7.6 (Maipo) Oracle Linux Server release 7.6 cpe:/o:oracle:linux:7:6:server root:[~]#   Below is my testing on a freshly installed server.  root:[~]# pwd /root root:[~]# ls -lad /root dr-xr-x---. 9 root root 4096 Aug 16 22:07 /root root:[~]# mkdir test root:[~]# ls -lad test drwxr-xr-x. 2 root root 4096 Aug 16 22:07 test root:[~]# root:[~]# useradd a root:[~]# passwd a Changing password for user a. New password: BAD PASSWORD: The password is a palindrome Retype new password: passwd: all authentication tokens updated successfully. root:[~]# chmod u+s test root:[~]# root:[~]# su - a [a@localhost ~]$ cd /root/test -bash: cd: /root/test: Permission denied [a@localhost ~]$ cd /root -bash: cd: /root: Permission denied [a@localhost ~]$ logout root:[~]# root:[~]# ls -lad /root dr-xr-x---. 10 root root 4096 Aug 16 22:07 /root root:[~]# chmod o+x /root root:[~]# root:[~]# su - a Last login: Fri Aug 16 22:08:54 CST 2019 on pts/0 [a@localhost ~]$ cd /root/test [a@localhost test]$ [a@localhost test]$ pwd /root/test [a@localhost test]$ ls -la . total 8 drwsr-xr-x.  2 root root 4096 Aug 16 22:07 . dr-xr-x--x. 10 root root 4096 Aug 16 22:07 .. [a@localhost test]$ touch file1 touch: cannot touch ‘file1’: Permission denied [a@localhost test]$ logout root:[~]# root:[~]# chmod o+w test/ root:[~]# root:[~]# su - a Last login: Fri Aug 16 22:09:31 CST 2019 on pts/0 [a@localhost ~]$ [a@localhost ~]$ cd /root/test [a@localhost test]$ touch file1 [a@localhost test]$ ls -la total 8 drwsr-xrwx.  2 root root 4096 Aug 16 22:11 . dr-xr-x--x. 10 root root 4096 Aug 16 22:07 .. -rw-rw-r--.  1 a    a       0 Aug 16 22:11 file1 [a@localhost test]$ mkdir folder1 [a@localhost test]$ ls -la total 12 drwsr-xrwx.  3 root root 4096 Aug 16 22:11 . dr-xr-x--x. 10 root root 4096 Aug 16 22:07 .. -rw-rw-r--.  1 a    a       0 Aug 16 22:11 file1 drwxrwxr-x.  2 a    a    4096 Aug 16 22:11 folder1 [a@localhost test]$   As you can see, it seems the files and folders the user a created in /root/test didn't inherit the owner and group of it. The owner and group is a and not root. Are there any problems with my testing? I'm new in Linux.

Why does the SUID bit have no effect when applied to directories in Linux? I clearly see that I can set it with 'chmod u+s'. But why does it not have "any" effect. What is the reason for implementing a way to SET it but not implementing any effect?


how do I put the text on a new row under a paragraph? My code is the following:  \paragraph{Title} Some text, Some text, Some text, Some text, Some text.   Right now It ends up like:  Title Some text, Some text, Some text, Some text, Some text.  I want it to be like:  Title  Some text, Some text, Some text, Some text, Some text.     Regards

I have a document which requires many levels of sectioning. I have sections, subsections and subsubsections, but require one more level below that. I can't change the sections to be parts and move everything up a level, as this document will eventually be included in another document which has parts/chapters already.  I see that the \paragraph command is used for defining the section level below subsubsection, but that doesn't produce headings in the same way that subsection and subsubsection do. Is there any way to either (1) change the \paragraph command so that it works like subsubsection but just adds another number - ie. 1.2.3.4 or (2) create a \subsubsubsection command to do the same thing?


What design principles can be used to achieve simplicity without diminishing the ability of the user to use an interface efficiently for complex tasks?  Specifically, I'm wondering which  I can use to achieve more with less. Principles that allow a designer to cover complex interface features with simplified, minimalist, design.

You have arrived on this page because you are clearly curious about underlying fundamentals that you can incorporate into your thought process when designing.  According to many that came before us, there are key principles that can be considered when creating an effective design. In the following answers, you will find useful theories from a variety of respected sources.  Use this question as a reference for navigating the variety of topics:  Gestalt Principles                  Other Fundamentals and Useful Information                  If you know of a topic that hasn't been covered here, please add an answer with references to respected resources and it will be added to the list.  Of course direct quotes and paraphrasing from respected resources are a must, but should be limited to a small paragraph per topic at most and referenced back to their source as thoroughly as possible.  A  has been posted before, but not to create a collection of snippets that are enlightening for graphic designers of any and all skill levels.


I have tried expanding the inequality with $\|x+cy\| = \langle x+cy,x+cy\rangle^{1/2} $ and using the properties of the inner product but to no avail.

Here's Prob. 8 in the Problems after Sec. 3.2 in Introductory Functional Analysis With Applications by Erwine Kreyszig:      Show that in an inner product space, $x \perp y$ if and only if $\Vert x + \alpha y \Vert \ge \Vert x \Vert$ for all scalars $\alpha$.    If $x \perp y$, then $\langle x, y \rangle = 0$; so for any scalar $\alpha$, we have  $$ \begin{align*} \Vert x + \alpha y \Vert^2 &= \langle x + \alpha y, x + \alpha y \rangle \\ &= \Vert x \Vert^2 + 2 \Re \bar{\alpha} \langle x, y \rangle + \vert \alpha \vert^2 \ \Vert y \Vert^2 \\  &= \Vert x \Vert^2 +  \vert \alpha \vert^2 \ \Vert y \Vert^2 \\  &\ge \Vert x \Vert^2.  \end{align*} $$ So  $$ \Vert x + \alpha y \Vert \geq \Vert x \Vert. $$  Am I right?  Now how to prove the converse? It is my guess that we will have to put in a particular value for $\alpha$.


I am getting this error:  The following packages have unmet dependencies: udev : Depends: libudev1 (= 204-5ubuntu20.2) but 204-5ubuntu20.4 is to be installed E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.   Then I've tried to apt-get dist-upgrade and I a similar error:  The following packages have been kept back: libudev1 udev 0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.   What should I do? I am Using ubuntu 14.04 64 bits. The output of sudo apt-get -f install is:  Reading package lists... Done Building dependency tree Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.   Using ubuntu 14.04 I really need help guys, sry for double posting

Occasionally, when I'm installing stuff, I get an error like the following:  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  package1 : Depends: package2 (>= 1.8) but 1.7.5-1ubuntu1 is to be installed E: Unable to correct problems, you have held broken packages.   How can I resolve this?


I have multiple *.tar.gz files. They all contain files with file name a, b, and c. Is there a way to grep string 'foo' only from file b under these multiple *.tar.gz files without extracting the files.

I'm trying to find out what modules  in cpan. So I've used  to mirror it. My problem is that I need to iterate through the archives that are downloaded, and grep the files that are in the archives. Can anyone tell me how I might do this? preferably in a way that tells me which file in the archive and what line it's on.  (note: they aren't all tarballs some are zip files)


So parse a text file and print out line 1 and line 14, and then do nothing with lines 15-46, and then print out line 47 and line 60, etc until the end of the file. So basically every 46 lines, print out the 1st and 14th line, repeatedly for every 46 lines until EOF

I have a large file and I would like print from each sequential 50 lines , the 15th and 25th lines.  sed -n '15,25p' inputfile   How to modify this command to print only lines 15 and 25 and to loop over each 50 lines in the file.


I misclicked when doing a review , and that was a terrible goof. Is there a way to fix it?

I (and probably many other people) have accidentally clicked the wrong button in reviews. For example, I just clicked the Leave Open button when I wanted to click Close. I think many people have done this. I think an ability to undo this would be appreciated.


I have recently installed Ubuntu 17.04 on dualboot with Win10, but for some reason it stopped working. Basically when I try to boot Ubuntu a black screen appears and nothing happens.      I would like avoiding reinstalling it if possible, but if it isn't, please tell me how to remove Ubuntu 17.04 and install 16.04.3 in it's place.

I dual booted ubuntu 11.04/11.10 a while ago with a USB stick and i want to uninstall it.   I would like to completely uninstall the old version and get 12.04.  I have a 64 bit laptop. Please help!


I recently asked about the safety of my travel to Miami.  Now I had to cancel my hotel in Miami and I will not take my flight to Miami. Instead I go to Vegas or NY.  On my ESTA appliance I had to name an address where I will stay in the U.S. I gave the address of the hotel I booked. Now I am concerned that I have to apply a new ESTA or change my old one, does anyone know how this works out? I don't want to end up being returned at the U.S. Airport.

I have an ESTA for my visit last Sept to NY and I know it is valid for 2years.  I am going to Las Vegas in May, do I have to update the address at which I will be staying?


John emailed 128 people to invite them to the restaurant's inauguration party. He asked these guests to send the email to 5 others in exchange for participation in a lottery where a free meal for two is won. Based on the assumptions made below, how many of those who received the email are expected to come to the party? Assumptions •half of the 128 people emailed the other 5. •1/4 of these sent the email to 5 others. •1/8 of these sent the email to 5 others •1/16 of these sent the email to 5 others. • No one received the email more than once. • 10% of those who received the email will go to the party. All help/ solutions appreciated!

Looking please for any help! John emailed 128 people to invite them to the restaurant's inauguration party. He asked these guests to send the email to 5 others in exchange for participation in a lottery where a free meal for two is won. Based on the assumptions made below, how many of those who received the email are expected to come to the party? Assumptions •half of the 128 people emailed the other 5. •1/4 of these sent the email to 5 others. •1/8 of these sent the email to 5 others •1/16 of these sent the email to 5 others. • No one received the email more than once. • 10% of those who received the email will go to the party. My attempt was the following: 128: 2= 64    64+5=69 128:4= 32      32+5=37 128: 8= 16    16+5=21 128:16= 8      8+5=13 10% of 140= 14 person 14 person will go to the restaurant’s inauguration party.


I have the following code:  ALTER TABLE users MODIFY id int unsigned;   Which throws the following error:  ERROR 1025 (HY000) at line 114: Error on rename of './mydb/#sql-146dd_1d' to './mydb/users' (errno: 150)   I'm fairly certain this is because of a foreign key issue, but I'd like to find more details on the error.  I seem to remember that there was something I could enter into the mySQL command line that would display a list of the most recent errors for various types of issues (including foreign key problems) along with more detail on the exact cause (like the tables involved).  Does anyone know what i am talking about?

I tried this in mysql:  mysql> alter table region drop column country_id;   And got this:  ERROR 1025 (HY000): Error on rename of './product/#sql-14ae_81' to './product/region' (errno: 150)   Any ideas? Foreign key stuff?


Please check my attached about Flash Player error on my android phone. I can see Utube, Facebook videos very well but some of the website showing like that error. How could I solve this problem?  Phone : Huawei U9200 P1 Version : ICS 4.0.3 Flash Player Ver : Adobe Air and Adobe Flash Player 11.1

I know that Adobe Flash Player is discontinued for Android devices, but is there an alternative way to continue using Flash on an Android device?  I have the APK of Flash Player 10, but I would like to use the most recent version.


Many time i facing the "java.lang.OutOfMemoryError: Java heap space" error, is there any problem with new keyword, because i used new keyword many time for creating object of class in web application.

I have an application that reads a CSV file with piles of data rows.  I give the user a summary of the number of rows based on types of data, but I want to make sure that I don't read in too many rows of data and cause OutOfMemoryErrors.  Each row translates into an object.  Is there an easy way to find out the size of that object programmatically?  Is there a reference that defines how large primitive types and object references are for a VM?  Right now, I have code that says read up to 32,000 rows, but I'd also like to have code that says read as many rows as possible until I've used 32MB of memory.  Maybe that is a different question, but I'd still like to know.


i was searching online tips to speed up the time of rendering, and i've found one screenshot which is like this   but in my case there is no option of GPU in the compute device section, have a look at my screenshot    am i missing any hardware ?

I want to enable GPU rendering, but there is no option in User Preferences > System:    Why is this? How can I get cycles to render using my GPU?


A few months ago I was on Grindr and a profile claiming to be a sugar daddy messaged me and I think now it's a scam, I should've known before but I was kind of desperate and in need of money at that time. I didn't give out my bank account, "just" my PayPal (not connected to my bank account) and we exchanged numbers. He told me he would send me an allowance of 3000.- every few weeks and I needed to pay for gift cards and send him codes in order to receive the money. This was the first time being in that kind of sugar dad situation. I had a strange feeling and blocked the number. A few days later another number messaged me, saying he is from the FBI, that they (FBI) have my address and valuable information about me, have their eyes on me in Switzerland (I live in Switzerland) and if I don't do what my sugar daddy asks me to, I'm going to jail. So I got scared, unblocked the number and messaged him again. I did buy another gift card with a code but then stopped again. I haven't messaged him and didn't reply to any of the messages he sent me. I really think now it's a scam. But he sent me "proof" photos of how another sugar babe "received" money (90'000 US dollars?)... I probably think it's fake or something but it got me scared again.I asked him if he knows my address because the "FBI" number knows but he didn't reply to my question, just telling me "they're the FBI, they know that" (which sounds like it's a scam) I've told him I didn't want to be his sugar babe anymore and he was telling me I could "go" after I made the deposit and pay for another gift card (which would be even more expensive than the one before).. I don't know what to do. I'm thinking about blocking the number again and also the "FBI" number.. because I really think it's a scam. But I'm afraid of any legal thing..like is there actually something he can do legally? I'm in Switzerland, he has a number from the USA. Also the "FBI" number was weird, a weird profile picture with an Avengers T-Shirt on it and there were a lot of grammatical spelling mistakes in that message that that number sent me when telling me that message above.

I got involved with an online person and we exchanged numbers and he told me he would pay me $500 a week allowance to hang out when our schedules permit and to message him. Looking over it, I should have known it was a scam but was a bit desperate so got involved.  He sent me a cashiers check which I deposited and, because I got worried, I called my bank and they put a hold on my account because they agreed with me that the check was probably fake. Now I have a sugar daddy scammer threatening me with FBI saying I'm a fraud, and saying he has my address which I did not give him, can he legally do anything? He also wanted me to forward 1500 dollars of the 2000 dollar check through zelle.    Awesome thank you so much! I wasn't sure if he could technically take legal action since I technically didn't follow through and hang out with him, this eased my mind!:)


I'm trying to write a class which can have about 50+ methods. The class is templated like this:  template <typename T> class xyz<T> { private:     void method1(int x, int at); public:     xyz();     ~xyz();     void method2(T a);     void method3(T a);     void metho(T a);     .. //Other methods };   Now I would like to implement these methods in a separate implementation .cpp file, so i would have to do something like this:  #include "xyz.h" template <typename T> xyz<T>::xyz() { }  template <typename T> xyz<T>::~xyz() { } template <typename T> void method1(T a){ .. } template <typename T> void method2(T a){ .. }   So as you can see, I have to make a template each time I implement a new method. Do I have any better way of doing this than making the template 50+ times?  So that I'd only make it once and can reuse it every time? Sorry if this is too obvious (I believe it is).

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


Note: I have marked this question as a duplicate of another question. But I am   keeping it nonetheless as it has an example and a clearly explained   answer, so hopefully it should help others.   -- I need to convert a string of Hex characters into base64 as done by this  in *nix.  For "5C78336D77D8DF448007D277DAD5C569"(Hex) I know the expected output is "XHgzbXfY30SAB9J32tXFaQ=="(base64).  But when I try converting it into binary and then base64 I get this:  [kent@server SrcFiles]$ echo "5C78336D77D8DF448007D277DAD5C569" | xxd -b 0000000: 00110101 01000011 00110111 00111000 00110011 00110011  5C7833 0000006: 00110110 01000100 00110111 00110111 01000100 00111000  6D77D8 000000c: 01000100 01000110 00110100 00110100 00111000 00110000  DF4480 0000012: 00110000 00110111 01000100 00110010 00110111 00110111  07D277 0000018: 01000100 01000001 01000100 00110101 01000011 00110101  DAD5C5 000001e: 00110110 00111001 00001010                             69. [kent@server SrcFiles]$ echo "001101010100001100110111001110000011001100110011001101100100010000110111001101110100010000111000010001000100011000110100001101000011100000110000001100000011011101000100001100100011011100110111010001000100000101000100001101010100001100110101001101100011100100001010" | base64 MDAxMTAxMDEwMTAwMDAxMTAwMTEwMTExMDAxMTEwMDAwMDExMDAxMTAwMTEwMDExMDAxMTAxMTAw MTAwMDEwMDAwMTEwMTExMDAxMTAxMTEwMTAwMDEwMDAwMTExMDAwMDEwMDAxMDAwMTAwMDExMDAw MTEwMTAwMDAxMTAxMDAwMDExMTAwMDAwMTEwMDAwMDAxMTAwMDAwMDExMDExMTAxMDAwMTAwMDAx MTAwMTAwMDExMDExMTAwMTEwMTExMDEwMDAxMDAwMTAwMDAwMTAxMDAwMTAwMDAxMTAxMDEwMTAw MDAxMTAwMTEwMTAxMDAxMTAxMTAwMDExMTAwMTAwMDAxMDEwCg==   Can anyone point me in the right direction?

Can anyone recommend a straightforward way/tool to convert hex to base64?  I'm using Linux and OS X.


From Alice in Wonderland:  She waited for some time without hearing anything more: at last came a rumbling of little cartwheels, and the sound of a good many voices all talking together: she made out the words: 'Where's the other ladder?  Why did the writer add an article with the plural noun voices?

In "Seeing like a state" of James C.Scott there is a sentence at the beginning of a paragraph (Acknowledgements xi):     There are a good many scholars whose writings opened up new   perspectives for me or provided outstanding analyses of issues that I   could not have hoped to study so comprehensively on my own.   What worries me is a good many scholars. Is this some type of inversion or ancient English? Is this grammatically right? Why is a here? I thought that appropriate version would be There are many good scholars. Am I wrong?


I have a 60D and have never had this problem before although I have never set the exposure for 30 minutes I am so disappointed its a great shot

I discovered red/blue/white pixels on my night photographs tonight. Trying to confirm this, I took a black image with the lens on and indeed I saw a whole lot of them (I didn't count them but at least a good fifty on the whole picture).   I'm not exactly sure if they are hot pixels, stuck pixels or anything else.  I quickly gave a check to my last exported JPEG files (I get RAW out of the camera) and couldn't find anything. After a quick search, I've seen that Lightroom is caring about those pixels after RAW conversion.  I've read that, with Canon DSLRs, there is a software process that could take care of that directly on my camera. I don't know if I can use it without getting things even more messy.   My question is: Considering my crazy pixels are not visible on my pictures, should I get too emotional about them? My camera is under warranty but is it really worth it to return it to Canon? If it's only to receive it back 1 month later after Canon just used the very same menu to map out the pixels, it's a bit ridiculous. Could this be a sign that my camera has a bigger problem?  It seems related to shutter speed. When shooting a black image at 1/250s I get nothing. When shooting the same setup but 1s, I get a few of them. The more I increase the shutter speed, the more crazy pixels I get.


I need to validate string input with regex, rules are:   String should not be number less than 2 and not bigger than 9999 (2-9999) String should not have zeros before number (ex: no 0002, 0022, 0222)   I really need to accomplish this by regex so any other solution is not acceptable.

I don't really understand regular expressions.  Can you explain them to me in an easy-to-follow manner?  If there are any online tools or books, could you also link to them?


I am working on $\displaystyle\int_0^\pi \frac{x\cos x}{1+\sin^2 x}\,dx$  First: I use integrating by part then get   $$ x\arctan(\sin x)\Big|_0^\pi-\int_0^\pi \arctan(\sin x)\,dx $$  then I have $\displaystyle -\int_0^\pi \arctan(\sin x)\,dx$ because $x\arctan(\sin x)\Big|_0^\pi$ is equal to $0$  However, I don't know how to integrate $\displaystyle -\int_0^\pi \arctan(\sin x)\,dx$  Can someone give me a hint?  Thanks


If the nucleus is densely positively charged, why don’t the protons in the nucleus repel from each other and move towards the orbiting electrons?  Because each proton is not only being repelled by the other protons, it is also being pulled by the oppositely charged electrons   Why don’t these conditions make the atomic model impossible? I understand that electrons are in energy levels start so cannot force their way into the nucleus, but why not the reverse?

Do the protons inside the nucleus repel each other by the electrostatic force? If they do, why doesn't the repulsion drive the protons apart so that the nuclei get disintegrated?


I have two objects, a function, and some console.logs:    let obj1 = {   value: "a" }  let obj2 = {   value: "b" }  console.log(obj1.value) console.log(obj2.value)   function change(obj1, obj2) {   obj1 = obj2;   obj2.value = "c";   console.log(obj1.value)   console.log(obj2.value) }  change(obj1, obj2);  console.log(obj1.value) console.log(obj2.value)     RESULT:     a b c c a c   and I expected:     a b c c c c   Can someone explain why value is A and not C?

The primitive types (number, string, etc.) are passed by value, but objects are unknown, because they can be both passed-by-value (in case we consider that a variable holding an object is in fact a reference to the object) and passed-by-reference (when we consider that the variable to the object holds the object itself).  Although it doesn't really matter at the end, I want to know what is the correct way to present the arguments passing conventions. Is there an excerpt from JavaScript specification, which defines what should be the semantics regarding this?


In English there is some flexibility in the placement of adverbs:     A: Also I ate the lasagna.   B: I also ate the lasagna.   C: I ate also the lasagna.   D: I ate the lasagna also.   There is a difference in nuance between these sentences, but I am not concerned with that here. My interest is in simple technical writing where it is most important that the reader be able to parse the sentence grammatically. That is, it should be clear that "also" is an adverb, and that "ate" is the verb being modified.  This is trickier for sentences containing long phrases:     Add numerically greater items to the list first.   Presumably the answer will depend on the native language of the reader. But I'd appreciate any specific or general advice, as I communicate daily with people who speak many different languages.  Edit: As many people pointed out, my examples are not good. Here are some examples from real life, edited to respect confidentiality:     While the attenuator is running, occasionally the bias will saturate and the output will sit at -4 V.   vs     While the attenuator is running, the bias will occasionally saturate and the output will sit at -4 V.   The reader's native language is Spanish.     In the past couple weeks we experimented with applying this segmentation to some of your images and found it made an accuracy improvement of 0.5-1.5%.   vs     We experimented in the past couple weeks with applying this segmentation to some of your images and found it made an accuracy improvement of 0.5-1.5%.   The reader's native language is Japanese.

For example:     The word rarely turns up outside of those contexts.      The word turns up rarely outside of those contexts.   Which one is correct and why?


Is it safe to use a computer during a storm that might involve lightning discharges? I'm talking about normal every day usage like browsing the web and gaming, not stuff like installing OS or BIOS updates. I'm mainly worried about permanent damage to my computer hardware, but if there are any additional risks involved, those can be relevant as well.  In case it matters, my computer is plugged into a surge protector () and I live in a normal Belgian residential house with 1 upper floor and an attic.

Generally when I hear the crack of thunder, my PC goes off immediately. Today I'm working though, and wondered - how bad is it to leave it on? If the power goes out, will it kill it?   I use a power strip - that protects it, right?


How can I view the remarks on an old bounty?   I could swear I knew how to do this at one point, but the bounty remark text doesn't seem to be available at /posts/.../timeline or /posts/.../revisions, nor is it in the PostHistory or Votes table on SEDE.

Possible Duplicate:          I put a bounty on  which already have had  on it, and I'm interested in seeing their custom messages.  This was  and I cannot seem to find the feature implemented anywhere in any form, so my question is:  Is there currently any way to see the custom messages of resolved and/or expired bounties?     Related:


Is there a way to change the user permissions of a content type? As I would not like the anonymous user to access a specific content type.

Is there a way to avoid anonymous users can see nodes of a content type, like a block or a view?  I can control the access with a view, but if I know the link for a node, I can  see it without first logging in.


I am trying to learn C#.net and now I want delete whith gridview this is my code  <asp:GridView OnRowDeleted="catGrid_RowDeleted" ID="catGrid" runat="server" AutoGenerateColumns="False" DataSourceID="gridSqlCat" CssClass="gridStyle">                     <Columns>                         <asp:BoundField DataField="dor_category" HeaderText="دسته بندی ها" SortExpression="dor_category" />                         <asp:ButtonField  Text="حذف" />                     </Columns>                 </asp:GridView>   and this cs code  protected void catGrid_RowDeleted(object sender, GridViewDeletedEventArgs e)     {      }   so what should I do?

I am using GridView control in  2005  using .  How can I delete a particular row from GridView.  I have written the following code. But it's not working...  DataRow dr = dtPrf_Mstr.NewRow(); dtPrf_Mstr.Rows.Add(dr); GVGLCode.DataSource = dtPrf_Mstr; GVGLCode.DataBind();  int iCount = GVGLCode.Rows.Count; for (int i = 0; i <= iCount; i++) {     GVGLCode.DeleteRow(i); } GVGLCode.DataBind();


I've been trying to figure out how to delete millions of files from a mounted NAS drive. The OS I'm accessing it from is RHEL 7.6.   The directory is actively being written to, with tens or hundreds of thousands of additional files per day.   When I try running a deletion technique, such as:  rsync -av --delete empty_dir/ millions_of_files_dir/   It will use lots of CPU/MEM at first, with the "sending incremental file list" message. This continues forever, with CPU/MEM usage slowly petering down to a minimal amount.   My theory is that this is happening because the file list never ends; there are endlessly more files being added.   SO: Is there a deletion technique which doesn't require a full list of files before deletion, but will "stream-delete" as it finds them?

We have an issue with a folder becoming unwieldy with hundreds of thousands of tiny files.  There are so many files that performing rm -rf returns an error and instead what we need to do is something like:  find /path/to/folder -name "filenamestart*" -type f -exec rm -f {} \;  This works but is very slow and constantly fails from running out of memory.  Is there a better way to do this? Ideally I would like to remove the entire directory without caring about the contents inside it.


There are $50$ apple trees in an orchard. Each tree produces $800$ apples. For each additional tree planter in the orchard, the output per tree drops by $10$ apples. I'm not sure if what my function in terms of the number of trees that models the total production of apples would be. I'm pretty sure it's $a(x)=(50+x)(800-10x)$. Also, what is the implied domain and range of the function used?

This is   in the University of Washington's precal book.  Sylvia has an apple orchard. One season, her 100 trees yielded 140 apples per tree. She wants to increase her production by adding more trees to the orchard. However, she knows that for every 10 additional trees she plants, she will lose 4 apples per tree (i.e., the yield per tree will decrease by 4 apples). How many trees should she have in the orchard to maximize her production of apples?  Instructing a precal class, I walked through my approach to answering this in class (without preparing) and ended up doing something strange that may have confused the students. How would you clearly explain a way to get the function for the number of apples that we are trying to maximize? More generally, how would approach answering this question? It'd be nice to collect a some different approaches to demonstrate to my students that there is not a single rigid correct way to solve a problem.


How can I replace multiple spaces in a string with only one space in C#?  Example:  PLNICI PERO 2165/HORNET SPACESPACESPACESPACESPACE   would be:  PLNICI PERO 2165/HORNET   And second:  Example:  SPACESPACESPACESPACESPACE      77.000   would be:  77.000   Have you any idea please? Thanks

How can I replace multiple spaces in a string with only one space in C#?  Example:  1 2 3  4    5   would be:  1 2 3 4 5


We know that if two matrix $A$ and $B$ commutes then $\exp(A+B)=\exp(A)\exp(B)$. I am trying to find two matrix that does not commute but $\exp(A+B)=\exp(A)\exp(B)$ is true for them.  Can anybody give exact example. Thanks

A few years ago, I did research in quantum mechanics, specifically dealing with generalized displacement operators. In such musings, BCH lights (or gets in, depending on your viewpoint) the way. A question that struck me today was: does $\exp(A+B) = \exp(A)\exp(B)$ hold if and only if $A$ and $B$ commute? Clearly, if they do commute this is true but I have not seen anything detailing the opposite direction. Given the complexity of BCH, I would be inclined to think that it's not simple to prove if it is true. I've thought about it on my own but haven't been able to come to any sort of conclusion one way or the other.


Let $F$ be a field and $\bar{F}$ be its algebraic closure. Is it true that $|\bar{F}:F|=\infty$ implies that the degree of the irreducible polynomials in $F[x]$ is unbounded?     I believe it is, and in this case an hint in the right direction for a proof would be enough, but I don't know where to begin

One very convenient property of $\mathbb{R}$ as a ring is that there is an upper bound for the degree of irreducible polynomials in $\mathbb{R}[x]$, as      If $f\in\mathbb{R}[x]$ has degree larger than $2$, then $f$ is reducible.   However, the proof as I know depends highly on the fact that $\mathbb{C}$ is algebraically closed, and the very nice property: $z\in\mathbb{C}$ is in $\mathbb{R}$ if and only if $z=\bar{z}$.  This makes a generalization to other integral domains rather difficult. So the problem is      For what kind of integral domain $R$, we have a finite upper bound on the degree of irreducible elements in $R[x]$?   Some most familiar examples are ruled out: in $\mathbb{Z}[x]$, $\mathbb{Q}[x]$ and $\mathbb{F}_{p}[x]$, there is not such a bound. Unfortunately these exhaust all integral domains about which I have a working knowledge.  Another result might help is , which says if we can find a prime ideal $\mathfrak{p}$ in $R$ such that $\mathfrak{p}^2\neq\mathfrak{p}$, then by picking $a\in\mathfrak{p}^2\backslash\mathfrak{p}$ we have an irreducible $a+x^d$, where $d$ can be arbitrary, and hence the upper bound is not possible.  So we only need to focus on domains where $\mathfrak{p}^2=\mathfrak{p}$ for all prime ideals. This seems to be a quite strong restriction but I am not sure what to make of it.  Can someone give a hint?  Thanks!


Both sentences are in the past, what is the difference?  Mr X had driven them home.  Mr X has driven them home.

Non-native speakers often get confused about what the various tenses  and aspects mean in English. With input from some of the folk here I've put together a diagram that I hope will provide some clarity on the matter.  I offer it as the first answer to this question. Consider it a living document. Input is welcome, and good suggestions will be  incorporated into the diagram.    Nota bene: What this is not is a discussion of whether there are  more than two tenses in English. , to which this question is not intended to supply arguments one way or the other.  Here, the aim is to provide an overview of what constructions English-speaking people use for conveying information about actions referring to past, present, and future, and to provide it first and foremost to precisely the people who are likely to use "tense" as a catch-all term in their search, rather than to linguists who know better.  Breaking News There is now an excellent ELU blog article titled  . It is highly recommended reading.


How do I export the sql table in mysql workbench to a .csv without separating every commas even in the column data? Thanks! Solution: One way is to use the Table Data Export Wizard. It worked for me.

Is there an easy way to run a MySQL query from the Linux command line and output the results in  format?  Here's what I'm doing now:  mysql -u uid -ppwd -D dbname << EOQ | sed -e 's/        /,/g' | tee list.csv select id, concat("\"",name,"\"") as name from students EOQ   It gets messy when there are a lot of columns that need to be surrounded by quotes, or if there are quotes in the results that need to be escaped.


Closures are functions that inherit variables from their enclosing environment. So lets see this code:  binaryServer = BinaryServer({port: 9001});  binaryServer.on('connection', function(client) {   console.log("new connection");    client.on('stream', function(stream, meta) {     stream.on('data', function(data){     //actions     });     stream.on('end', function() {     //actions     });   }); });   So, I am correct if I say: " function(data){//actions} is a closure because inherits the variables of enclosing environment (like the object client) "? Because of my experiences that's what happening.

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen  given on Wikipedia, but unfortunately it did not help.


I flagged  as being off-topic and requested it be migrated to . However, it's suggesting I flagged it as a duplicate and/or should be closed:    While closing as off-topic includes a listing for a possible duplicate    it seems incorrect.

I recently flagged a post on SO as "Unclear what you're asking". Afterwards, for whatever reason, I clicked flag again and found this:    Is there any reason it says I've raised a duplicate flag too when I'm positive I have not? Is this a bug? The question, as of 2:56 PM UTC, 11 September, 2013, has only existed for 26 minutes and the flag doesn't exist in my flag history:    Note: There are several similar questions:       The first was never answered and the second is unrelated as it appears the person asking did, in fact, raise the flag they assumed they hadn't raised.