# How to draw curves (cardioid, lemniscate, devil's curve)?

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1. Aug 9, 2015

### ydonna1990

Hi everyone,

Thanks for visiting my post. I was wondering if you guys know what kind of software I must use to draw complicated curves. I already have the equations. For example, for lemniscate I would use following:
2(x^2+y^2)=25(x^2-y^2)

I appreciate the help.

2. Aug 9, 2015

### Staff: Mentor

There are many programs that can plot those curves.
Your specific example are two straight lines.

3. Aug 9, 2015

### ydonna1990

The example that I posted is Lemniscate's equation in Cartesian coordinates. Please refer to https://en.wikipedia.org/wiki/Lemniscate_of_Bernoulli
Anyway, I have the equations and I would like to draw the curves.

And as you said, I know that there are many software programs available. Can you provide me with a name.

Thanks.

4. Aug 9, 2015

### Staff: Mentor

Your formula is missing a square on the left side.

This list has many programs.
Gnuplot, Maple, Mathematica and Matlab are some of the more prominent plotting programs in this list.
Then why did you ask which program you "must" use if there are so many options?

Edit: We don't delete threads, but I can close this one.

Last edited: Aug 9, 2015
5. Aug 9, 2015

### Staff: Mentor

Follow the link in post #2 and you will have one name.

6. Aug 9, 2015

### ydonna1990

The equation is 2(x^2+y^2)^2=25(x^2-y^2). I wrote my post in a hurry and didn't see the error until now.

Also as for the usage of the word "must", it could have easily been replaced with words like "could, should, may", etc. It's just a technicality. I apologize if you misunderstood.

Thanks for the list. It will come in handy.

7. Aug 9, 2015

### ydonna1990

Well, one name, two names, three names.

Happy to be given a list eventually. I will def check out Gnuplot and Maple.

8. Aug 9, 2015

### micromass

Check geogebra. It's free and it can handle these kind of implicit equations perfectly.

9. Aug 9, 2015

### ydonna1990

It's great. Thank you. I am trying it out now. I am trying to use CAS but it doesn't seem to plot. Any ideas?

10. Aug 9, 2015

### micromass

What's CAS? Is that part of geogebra, or does it mean you're using another Computer Algebra System?
If you're using geogebra, you just need to go all the way below to "input" and type your equation 2(x^2+y^2)^2=25(x^2-y^2). That should plot it immediately.

11. Aug 9, 2015

### ydonna1990

CAS is part of geogebra. I just downloaded it and I am looking at it now. O.K. I will do that.

12. Aug 9, 2015

### micromass

Oh ok, I see it now. You don't need this CAS at all. It's better just to close that window.

13. Aug 9, 2015

### ydonna1990

Alright. Do you think it'd be ok if I pm you some time later? (currently I am working on something). You are kind. I really appreciate your help.

14. Aug 9, 2015

### micromass

Sure, I don't mind.