Help sketching equation into 3d graph

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.

Answer 1

[Star Strider]

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')

.

Answer 2

[Joseph Cheng]

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

[Joseph Cheng]

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]

Owh sry actually I did insert the meshgrid. Updated my post. But still the error shows up.

Answer 3

[Girijashankar Sahoo]

% 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);