RMS error of matrices

Hi,

I have 2 large matrixes (2048x2048), and have taken one away from the other to get a 'difference' matrix. I want to quantify this matrix by using an RMS error, however if I use a standard RMS error formula I get another 2048x2048 matrix.

Is there a way to get a single representative RMS value out?

Thanks,

Richard

[Todd Pierce]

Hi there,

I am in a simlar position to yourself however, i want to maintain the matrix with all the rms values in, what initial line did you type in to get the rms for every value in the matrix whilst maintaining the shape.

Answer 1

[Walter Roberson]

Isn't it usually

sqrt(mean(A(:).^2 - B(:).^2))

Answer 2

[darksideofthemoon101]

I've been using

rms = sqrt((A - B)^2))

How dissimilar are these equations?

[Walter Roberson]

When A and B are arrays then A-B is an array, and (A-B)^2 is

(A-B)*(A-B) which is a matrix multiplication which will produce an output the same size as A (in this case.) sqrt() of that would then be the same size.

Nothing in your code calculates the _mean_ portion of "RMS". Root MEAN square.

Possibly I should have suggested

sqrt(mean((A(:)-B(:)).^2))

but I am too tired to look up the definition at the moment.