I got a function of three parameters that I wanted to plot in matlab and I varied the values of the parameters (50 values for each parameter) for creating a multidimensional array 50x50x50. At first I want to plot it with surf, then with contourn3, but I don't know how to do this. I want to see the trend of this function.
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Possible dup: stackoverflow.com/questions/9806190/…Murkantilism– Murkantilism2013-05-14 14:00:15 +00:00Commented May 14, 2013 at 14:00
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1 Answer
If I understand right, you have some sort of function like value = fun(parmA, parmB, parmC), and want to visualize how value changes w.r.t. the parameters. Unfortunately there is no way to visualize all of the data at once in a single graphic. You have to choose one of the dimensions to hold constant.
We can visualize 3-D data using a surface plot, surf(), or level contours contour(). These work when we have something like value = fun(parmA, parmB), or z = fun(x,y). So the best alternative you have is step through one of the dimensions and generate a new surface or contour plot for each value.
Using a short delay, you can actually generate a video. Here is a simple example. You might have to do a little extra work if you want to hold the axes constant throughout.
clear all; close all; clc
% create your parameters
x = linspace(-50,50,51);
y = linspace(-100,100,52);
z = linspace(0,50,50);
% A function of three variables
fun = @(x,y,z) sqrt(x^2 + y^2 + z^2);
% Preallocate
vaue = zeros(50,50,50);
% Populate the data matrix
for i = 1:numel(x)
for j = 1:numel(y)
for k = 1:numel(z)
value(i,j,k) = fun(x(i),y(j),z(k));
end
end
end
% Generate a new surface or contour plot for each value of "z"
for k = 1:numel(z)
figure(1)
%contour(x,y,value(:,:,k)');
surf(x,y,value(:,:,k)');
title(sprintf('z = %f',z(k)));
pause(0.1);
end
