Help sketching equation into 3d graph

2 views (last 30 days)
What I got so far for the equation
Z=5-sqrt(1-x.^(2)-(y-abs(x)).^2).*cos(30.*(1-x.^(2)-(y-abs(x)).^(2)))
Then I tried these lines
x=linspace(-1,1, 200);
y=linspace(-1, 1.5, 200);
[X,Y]=meshgrid(x,y);
Z=5-sqrt(1-x.^(2)-(y-abs(x)).^2).*cos(30.*(1-x.^(2)-(y-abs(x)).^(2)))
zlim([1,6]);
surf(X,Y,Z);
It gave me "Z must be a matrix, not a scalar or vector." error.

Accepted Answer

Star Strider
Star Strider on 1 Jun 2021
The error it throws when I run it here is:
X, Y, Z, and C cannot be complex
This is likely because of the negative values in ‘x’ and ‘y’, however I did not do an in-depth analysis.
Dealing with that produces —
x=linspace(-1,1, 200);
y=linspace(-1, 1.5, 200);
[X,Y]=meshgrid(x,y);
Z=@(x,y) 5-sqrt(1-x.^(2)-(y-abs(x)).^(2).*cos(30*(1-x.^(2)-(y-abs(x)).^(2))));
figure
surf(X,Y,real(Z(X,Y)))
grid on
zlim([1,6])
title('Real Z')
figure
surf(X,Y,imag(Z(X,Y)))
grid on
% zlim([1,6])
title('Imag Z')
figure
surf(X,Y,abs(Z(X,Y)))
grid on
zlim([1,6])
title('|Z|')
figure
surf(X,Y,Z(X,Y))
Error using surf (line 71)
X, Y, Z, and C cannot be complex.
grid on
zlim([1,6])
title('Complex Z')
.

More Answers (2)

Joseph Cheng
Joseph Cheng on 1 Jun 2021
what you'll need to do is use the function meshgrid() which will then create a 2D matrix for both x and y such that you can get the pair combination of x and y of your linspace
[x y]=meshgrid(x,y);
%then do your Z
  2 Comments
Joseph Cheng
Joseph Cheng on 1 Jun 2021
As right now
x = 1x200 matrix
y = 1x200 matrix
so since you're using .* and .^ in your Z equation you'll also get a 1x200 for Z.
using meshgrid to generate the 2D grid of x and y combinations such that you can get the range of Z values for x between -1 and 1 and y over the range of -1 and 1.5.
Muhd Farhad
Muhd Farhad on 1 Jun 2021
Owh sry actually I did insert the meshgrid. Updated my post. But still the error shows up.

Sign in to comment.


Girijashankar Sahoo
Girijashankar Sahoo on 1 Jun 2021
% Size of of your output Z must be 200x200 matix
% Try this code for 3D output
x=linspace(-1,1, 200);
y=linspace(-1, 1.5, 200);
for i=1:length(y)
for k=1:length(x)
Z=5-sqrt(1-x.^(2)-(y-abs(x)).^(2).*cos(30*(1-x.^(2)-(y-abs(x)).^(2))));
end
end
zlim([1,6]);
T=rand(200)
surf(x,y,T);

Categories

Find more on Colormaps in Help Center and File Exchange

Products


Release

R2021a

Community Treasure Hunt

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

Start Hunting!