Plotting a function of 3 variables ?

Hi,

I'm trying to visualize a function of 3 variables v = f(x,y,z). So I'm wondering is there any appropriate plotting function in Matlab? What I am thinking of is a 3-D lattice of markers with the colour of the marker indicating the function value, like a 3-D scatter plot with each point being a different coloured sphere with the colour indicating the function's magnitude at that point. The spheres would be small relative to the distance between adjacent spheres (the x,y,z coordinates to be plotted will be uniformly spaced) so that the figure could be rotated and viewed from all angles while still being able to see any patterns or trends through the entire lattice. Is there any command to achieve something like this ?

Thanks

Answer 1

[Walter Roberson]

spheresize = 10;
scatter3(x, y, z, spheresize, v)

Answer 2

[Eric]

See the documentation for scatter3. http://www.mathworks.com/help/techdoc/ref/scatter3.html) The last input argument lets you pass color information for each point. I've successfully used the two-dimensional version of this function in the manner you describe.

Use either the icons on the figure window to zoom and rotate or use the zoom and rotate3d commanders from the command line.

Good luck,

Eric

Answer 3

[julie]

I need to do the same kind of thing. How do you do to make the color parameter of scatter3 take the value of your function v or to associate this value to a RGB row vector?

[Walter Roberson]

As I indicated above,

spheresize = 10;
scatter3(x, y, z, spheresize, v)

The 5th parameter, v, is the position for color. It may be a column vector the same length as x, or it may be an RGB array, v(K,:) corresponding to x(K), y(K), z(K)

[julie]

Thanks! that's OK, I thought the function accept only RGB vector.