Covariance Matrix Rotation

Hi, I have a matrix 3 by 3 and I want to rotate it with theta and phi angles (result of spherical coordinates), counterclockwise. I have the following function;

 function [NewMatrix] = SphericalRotation(Matrix, theta, phi, ScaleRatio)
            M1 = [cos(theta) -sin(theta) 0; sin(theta) cos(theta) 0; 0 0 1];
            M2 = [1 0 0; 0 cos(phi) -sin(phi); 0 sin(phi) cos(phi)];
            NewMatrix = ScaleRatio^0 * M2 * M1 * Matrix * M1' * M2';
 end

When;

 Matrix = [4 0 0; 0 4 0; 0 0 4], 
 theta = 0.78, 
 phi=0.61,
 scaleRatio= 1.2 (Not important, results 1 always right now),

I get

 NewMatrix=[4 0 0; 0 4 0; 0 0 4]

I don't think this is correct, I should get something different, it is not rotated at all. I believe I am missing sth. very basic. Any help greatly appreciated. Thanks

[bym]

why are you multiplying by the rotation matrices twice?

M2*M1*M1'*M2'

ans =

1 0 0

0 1 0

0 0 1

[Umit]

I matrices, I believe it has to be in this way, for vectors it is just M2*M1*Vector

[Jim]

Your test matrix Matrix represents a spherical probability distribution, i.e., the principal values are all identical. There's no way to orient a sphere, which is why your function returns an unaltered output. Try setting Matrix = [10 0 0; 0 3 0; 0 0 1] and you'll see a difference in the output.