MATLAB: To 3Dplot a function that is inside a nested for loop

3dplotfunctionnested for loop

I am trying to plot a 3D figure out of 2D gaussian function 'z' . I need to plot the z values as a 3D plot
clear all;
clc;
XMin = -2.5;
XMax = 2.5;
YMin = XMin;
YMax = XMax;
increment = 0.01;
sigma = 1;
for x = XMin:increment:XMax
    for y = YMin:increment:YMax
        z = exp((-((x.^2)+(y.^2))./2)*(sigma.^2));
    end
end
% Trying to plot a 3D figure

Best Answer

You are not saving the values of ‘z’ in your loop as a matrix.
However there is a more efficient way to do what you want, avoiding the (explicit) loops entirely: 
XMin = -2.5;
XMax = 2.5;
YMin = XMin;
YMax = XMax;
increment = 0.01;
sigma = 1;
Xv = XMin:increment:XMax;                                       % Assign Vector

Yv = YMin:increment:YMax;                                       % Assign Vector
z = @(x,y) exp((-((x.^2)+(y.^2))./2)*(sigma.^2));               % Anonymous Function (For Ceonvenience)
[Xm,Ym] = ndgrid(Xv,Yv);                                        % Generate Grid Matrices
figure
surf(Xv, Yv, z(Xm,Ym), 'EdgeColor','none')                      % Evaluate & Plot
grid on
Your grid is very dense, so setting the 'EdgeColor' to 'none' turns off the edges, allowing you to see the surface patches easily.
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