How do I define the index within the array?

Matlab, index of minimum values in array along one dimension?

• Assume I=n*m*p [n=2, m=2, p=3 for example below] I(:,:,1) = 8 26 40 80 I(:,:,2) = 43 18 91 26 I(:,:,3) = 15 87 14 58 I want to create a matrix that shows the index of the minimum value going across the 3rd coordinate. For example, for above it would be J=[1 2 3 2] Since [8, 43, 15] has min at index 1 [26, 18, 87] has min at index 2 [40, 91, 14] has min at index 3 [80, 26, 58] has min at index 2 I can do it with a double for loop, but would like to know how to do it vectorized, as the first two dimensions could be quite big. (The third dimension <10). Thanks! -MIke

• Answer:

  You just need to read the syntax on the max function. Try [val,ind]=max(J, [ ], 3). This gives you the value (val) and the index (ind) of the max of the tensor J along the third dimension.