<p>Your final line</p>
<blockquote>
<p>This figure is only for representation.</p>
</blockquote>
<p>pretty much answers your question.</p>
<p>When explaining these concepts you want to draw something that is easy to understand, i.e. does not have too many irregularities but is also not <em>too</em> regular.</p>
<p>Linearity is a special attribute of functions. General curves show that there is usually no need for this assumption.</p>
<p>Continuity is a frequent though not omnipresent assumption in economics.
Rather than throw in a few points of discontinuity and provide reasons for them, it is easier to explain general concepts with continuous curves. This does not mean that most functional relationships are indeed continuous; there are plenty of counterexamples, but where this is important, there are usually discontinuous graphs and explanations thereof.</p>

CC BY-SA 4.0
2021-03-25T13:58:13.560Z
You are right. This is essentially a very broad and not very meaningful question. Can you explain (possibly in gist) why [some](https://en.wikipedia.org/wiki/Demand_curve#/media/File:SMD_Demand_Curve.svg) demand curves are not just upward/downward sloping but rather has so many waves? Is it because of the various factors that affect demand (like : income, price of related products, preferences of the consumers, etc)? I learnt that conventionally these factors are not accounted.
not tdm's twin
CC BY-SA 4.0
2021-03-25T21:18:30.500Z
I cannot, but I suggest you read the referenced paper and post a new question if something in it puzzles you.
Giskard
CC BY-SA 4.0
2021-03-25T11:43:35.683Z
2021-03-26T22:19:38.280Z
2021-03-26T22:19:38.280Z
Giskard
<p>I always see curves (such as in dark blue below) and not any other type of (function) image. May I get a reason for why it is always like that?</p>
<p><a href="https://i.sstatic.net/Ie8oG.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Ie8oG.png" alt="enter image description here" /></a></p>
<p>This figure is only for representation.</p>

CC BY-SA 4.0
2021-03-25T09:08:29.210Z
What exactly do you mean by curves? Non-linear? Continuous? Differentiable?
Giskard
CC BY-SA 4.0
2021-03-25T09:53:22.473Z
@Giskard I don't mean anything in particular. I have always observed that the function images tend to be in the form of a curve (usually continuous) or basically any non-linear function. For example, the shape of the Demand Function is usually a non-linear and continuous (depending on the Price). I am very new to the subject and can not provide too many examples.
not tdm's twin
CC BY-SA 4.0
2021-03-25T10:38:11.913Z
I really think this needs details or clarity or should be closed; broadly speaking you can call curve virtually any non-straight line. Many relationships, not just in economics but in all fields of science are nonlinear- unless you specify exactly what topic you are interested in not much more can be said about that. You can give reasons why demand should be non linear or why costs should be non-linear but asking to give these reasons for all curves in economics would be way too broad.
1muflon1
CC BY-SA 4.0
2021-03-26T11:15:14.843Z
What other kind of image is there????
Criticize SE actions means ban
<macroeconomics><microeconomics><nonexpert>
Why do most function images take the form of a curve?
not tdm's twin
# Why do most function images take the form of a curve?

(Asked by: username_0 on 2021-03-25)

I always see curves (such as in dark blue below) and not any other type of (function) image. May I get a reason for why it is always like that?

[![enter image description here](https://i.sstatic.net/Ie8oG.png)](https://i.sstatic.net/Ie8oG.png)

This figure is only for representation.

**Tags:** macroeconomics, microeconomics, nonexpert

> **Comments:**
> **username_1**: What exactly do you mean by curves? Non-linear? Continuous? Differentiable?  
> **username_0**: @username_1 I don't mean anything in particular. I have always observed that the function images tend to be in the form of a curve (usually continuous) or basically any non-linear function. For example, the shape of the Demand Function is usually a non-linear and continuous (depending on the Price). I am very new to the subject and can not provide too many examples.  
> **username_2**: I really think this needs details or clarity or should be closed; broadly speaking you can call curve virtually any non-straight line. Many relationships, not just in economics but in all fields of science are nonlinear- unless you specify exactly what topic you are interested in not much more can be said about that. You can give reasons why demand should be non linear or why costs should be non-linear but asking to give these reasons for all curves in economics would be way too broad.  
> **username_3**: What other kind of image is there????  

---

## 1 answers

### Answer by username_1 on 2021-03-25. Score: 5 | Accepted answer

Your final line

> This figure is only for representation.

pretty much answers your question.

When explaining these concepts you want to draw something that is easy to understand, i.e. does not have too many irregularities but is also not *too* regular.

Linearity is a special attribute of functions. General curves show that there is usually no need for this assumption.

Continuity is a frequent though not omnipresent assumption in economics.
Rather than throw in a few points of discontinuity and provide reasons for them, it is easier to explain general concepts with continuous curves. This does not mean that most functional relationships are indeed continuous; there are plenty of counterexamples, but where this is important, there are usually discontinuous graphs and explanations thereof.

> **Comments:**
> **username_0**: You are right. This is essentially a very broad and not very meaningful question. Can you explain (possibly in gist) why [some](https://en.wikipedia.org/wiki/Demand_curve#/media/File:SMD_Demand_Curve.svg) demand curves are not just upward/downward sloping but rather has so many waves? Is it because of the various factors that affect demand (like : income, price of related products, preferences of the consumers, etc)? I learnt that conventionally these factors are not accounted.  
> **username_1**: I cannot, but I suggest you read the referenced paper and post a new question if something in it puzzles you.  

---

