# Error using surf Z must be a matrix, not a scalar or vector.

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Peter on 21 Feb 2024
Edited: Hassaan on 21 Feb 2024
I was trying to plot using the following code but i get this error. Please help me. Thank you!
x=(0:0.1:pi);
y=(0:0.1:pi);
[X, Y]= meshgrid(x,y);
Z=(sin(0.3*x)+(1+1./(1+cos(y).^2)));
surf(X, Y, Z);
Error using surf
Z must be a matrix, not a scalar or vector.

KSSV on 21 Feb 2024
Edited: KSSV on 21 Feb 2024
You have to use X and Y i.e matrix in the calculation Z.
x=(0:0.1:pi);
y=(0:0.1:pi);
[X, Y]= meshgrid(x,y);
Z=(sin(0.3*X)+(1+1./(1+cos(Y).^2)));
surf(X, Y, Z);

Hassaan on 21 Feb 2024
Edited: Hassaan on 21 Feb 2024
To correct this, you need to use X and Y from the output of meshgrid in your calculation of Z, ensuring that Z is a matrix where each element corresponds to a combination of x and y values.
x = 0:0.1:pi;
y = 0:0.1:pi;
[X, Y] = meshgrid(x, y);
Z = sin(0.3*X) + (1 + 1./(1 + cos(Y).^2));
% Create the surface plot
surf(X, Y, Z);
% Add a title and axis labels
title('Surface Plot of Z = sin(0.3X) + (1 + 1./(1 + cos(Y).^2))');
xlabel('X axis');
ylabel('Y axis');
zlabel('Z axis');
% Add a colorbar to the figure to show the mapping of color to the Z values
colorbar;
sin(0.3*X) and cos(Y).^2 compute the sine and cosine values over the matrices X and Y, respectively, producing a matrix Z that matches the dimensions of X and Y. This makes Z suitable for plotting with surf. The key here is to use X and Y after they've been generated by meshgrid for any operations that contribute to the Z values.
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