0 个投票

I have the equation:
x^2 + y^2 + z^2 = 1
How do I tell Matlab to plot this in the 3D plane? This is just one equation, but I will need to plot several in the 3D plane.

5 个评论
显示 3更早的评论 隐藏 3更早的评论

Marco Froelich
Marco Froelich 2017-7-5
The problem is not the plot command, rather the actual code for the formula. When I enter it, I get an error message saying:
The expression to the left of the equal sign is not a valid target for an assignment.
Marco Froelich
Marco Froelich 2017-7-5
Another error comes up with another formula: x = y + z
undefined function or variable y
Adam
Adam 2017-7-5
I think you would need the Symbolic Toolbox to do this kind of thing. I only glanced at the equation initially and didn't register the '= 1' at the end of it which turns it into something that base Matlab doesn't cater for.
I've never worked with equation solving in Matlab myself so hopefully someone else can provide more information on usage of the Symbolic Toolbox or whatever other functionality is needed for this.
Marco Froelich
Marco Froelich 2017-7-5
No but I am not trying to solve the equation, only plot its graph. But fair enough, thank you

请先登录，再进行评论。

请先登录，再回答此问题。

 采纳的回答

Ari
Ari 2017-7-5

3 个投票

Your equation x^2 + y^2 + z^2 = 1 resembles a surface and can be plotted with the fsurf command in MATLAB which will need your function handle as an argument. You will need to rewrite the function as z expressed in terms of x and y as follows.
z = @(x,y) sqrt(x.^2 + y.^2 - 1); % function handle to anonymous function
fsurf(z)
You can find other methods to do the same from the documentation here .
For information on function handles see here .
For plotting multiple 3D surfaces on the same graph you can use the hold command as below. The hold command will plot subsequent plots in the same figure.
z1 = @(x,y) sqrt(x.^2 + y.^2 - 1);
z2 = @(x,y) sqrt(x.^2 + 2*y.^2 - 5);
fsurf(z1)
hold on
fsurf(z2)

3 个评论
显示 1更早的评论 隐藏 1更早的评论

Marco Froelich
Marco Froelich 2017-7-10
Im sorry, but I just tried this and it gave me a weird graph I will show you. The equation above is supposed to give me sphere.
Marco Froelich
Marco Froelich 2017-7-10
I found it. Input function, with the command fimplicit3
Sakib Mahmud
Sakib Mahmud 2019-9-8
This equation will give half of a sphere. The rest half will come from -sqrt...

请先登录，再进行评论。

更多回答（1 个）

HARSH MEHTA
HARSH MEHTA 2021-4-22

0 个投票

x^2 + y^3 + z^4 = f(x,y,z)
and X^2(y^3)(z^4) = f(x,y,z) how can i polt this both differently

类别

在 帮助中心 和 File Exchange 中查找有关 2-D and 3-D Plots 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by