PDA

View Full Version : Matlab 3D problem


debwaldy
Mar30-08, 08:59 AM
1. The problem statement, all variables and given/known data
Hi all! I'm trying to solve the following problem but I'm not too sure of a few things.
Write Matlab instructions to plot a three dimensional Gaussian:

A = A0exp((x^2 + y^2 + z^2)/w^2)

choosing appropriate values for A0,w and range of coordinates.


2. Relevant equations
I'm guessing i have to use the plot3 command but after that I'm lost


3. The attempt at a solution
I dont know how to choose appropriate values for all of the variables.And what is w?
I'm a bit lost so I'd really appreciate any hints or tips to point me in the right direction thanks debs:smile:

LeBrad
Mar31-08, 07:57 AM
1. The problem statement, all variables and given/known data
Hi all! I'm trying to solve the following problem but I'm not too sure of a few things.
Write Matlab instructions to plot a three dimensional Gaussian:

A = A0exp((x^2 + y^2 + z^2)/w^2)

choosing appropriate values for A0,w and range of coordinates.


2. Relevant equations
I'm guessing i have to use the plot3 command but after that I'm lost


3. The attempt at a solution
I dont know how to choose appropriate values for all of the variables.And what is w?
I'm a bit lost so I'd really appreciate any hints or tips to point me in the right direction thanks debs:smile:

w is a parameter of your Gaussian, make it bigger and the distribution should flatten out.

What exactly do you want to plot? You can't plot A(x,y,z) on a 3D plot because A depends on 3 variables so you would need a 4D plot.

If you want to plot a Gaussian distribution of 2 variables, run the following code in Matlab:

clear;
pts = -5:.1:5;
N = length(pts);
X = reshape(repmat(pts,1,N),N,N);
Y = reshape(repmat(pts,N,1),N,N);
Z = exp(-X.^2-Y.^2);
figure;surf(X,Y,Z)

Is that the type of plot you are trying to produce?