compare the absolute value of each element from two matrices

I have two matrices A and B with the size NxM and I want to compare the absolute value of each element for the two matrices and return the bigger value and then to store the real value in a new matrix.

Any suggestions please

Many thanks in advance

[Image Analyst]

How are we suppose to know which elements from A or B are the "real" values? Or do you mean "real" as in complex - are A and B complex numbers? Please give a small numerical example.

[Jack_111]

for example a = [1 -2 -3; 4 5 -6] and b = [3 2 1; 8 9 -3] and when I will compare the absolute values and store them in another matrix using c = max(abs(a),abs(b)); that means the output will be

c = [3 2 3 ; 8 9 6] but I want it to return c = [3 2 (doesn't matter) -3 ; 8 9 -6] (in the case where they are equal, it doesn't matter what it will return).

I hope you got my point. I don't want the absolute value to be registered but just the real value which is in our example (-6 and -3) nut the absolute value is just to compare

[Image Analyst]

OK. Good. Calling it the "real" value instead of the "max" value was a major oversight initially. But now that you've clarified it, it looks like you now have two correct solutions. Thanks for accepting one of them. You can also vote for both of them too, even though you can accept only one.

Answer 1

[Guillaume]

Concatenate A and B along the third dimension, get the second output of max along the 3rd dimension of the absolute of that 3d matrix to get the z index. The tricky bit is then using that z value to select A or B. Summing each matrix multiplied by a logical matrix should do it:

a = [1 -2 -3; 4 5 -6]
b = [3 2 1; 8 9 -3]
ab = cat(3, a, b);
[~, idx] = max(abs(ab), [], 3);
c = a.*(idx==1) + b.*(idx==2)

Answer 2

[the cyclist]

absA = abs(A);
absB = abs(B);

I'm not sure what you mean by "compare ... and return the real value". Larger? Smaller? Difference?

[Jack_111]

for example a = [1 -2 -3; 4 5 -6] and b = [3 2 1; 8 9 -3] and when I will compare the absolute values and store them in another matrix using c = max(abs(a),abs(b)); that means the output will be

c = [3 2 3 ; 8 9 6] but I want it to return c = [3 2 (doesn't matter) -3 ; 8 9 -6] (in the case where they are equal, it doesn't matter what it will return).

I hope you got my point. I don't want the absolute value to be registered but just the real value which is in our example (-6 and -3) nut the absolute value is just to compare

[Jack_111]

Sorry that my question wasn't phrased well