Plotting a 3d gaussian function using surf
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Desmond Johnson
on 27 Feb 2015
Commented: Xiang Chen
on 16 Oct 2018
Let me start off by saying that I am extremely new to MATLAB. I would to use these functions and turn them into a 3d plot using surf. I have already made a mesh grid of my x and y but I am confused on how to plug my gaussian function in as Z. I would like the surf plot to look like this http://i.stack.imgur.com/QiTPe.png
x=randn(1,10000);
y=x';
[X,Y]=meshgrid(x,y);
z=(1000/sqrt(2*pi)*exp(-X.^2/2))
surf(x,y,z);shading interp
Thanks in advance for the help.
1 Comment
Accepted Answer
Star Strider
on 27 Feb 2015
Edited: Star Strider
on 27 Feb 2015
This works:
N = 3.0;
x=linspace(-N, N);
y=x;
[X,Y]=meshgrid(x,y);
z=(1000/sqrt(2*pi).*exp(-(X.^2/2)-(Y.^2/2)));
surf(X,Y,z);
shading interp
axis tight
Experiment to get the result you want.
5 Comments
Star Strider
on 28 Feb 2015
My pleasure.
You have to use a linear vector in x and y, as did I with linspace. I see no reason to use randn here, since it is by definition random and will create very strange matrices with meshgrid.
To experiment, do a simple surf plot of the meshgrid outputs using a randn vector and using linspace for x and y. Use different randn calls for x and y each in order to avoid the ‘banding’ you saw in the plot you posted.
If you want to use randn at all to look at the distribution of the points, consider using scatter3:
x = randn(1,10000);
y = randn(1,10000);
zf=@(X,Y) (1000/sqrt(2*pi).*exp(-(X.^2/2)-(Y.^2/2)));
z = zf(x,y);
figure(1)
scatter3(x, y, z, 'b.')
grid on
Rotate it in the GUI to get an interesting perspective on the density of the distribution.
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