Max/Min of nonzero rows/cols
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I have a Matrix, A.
I want to find the max and min for every row and column in A, excluding the zero entries.
I have coded it using For loops, but it is too slow. I need it to be all vectorized. Any help is greatly appreciated.
More Answers (1)
Geoff on 12 Apr 2012
When you say 'for every row and column', do you mean a single max and min for the entire matrix? This would do it:
nzmin = min(A(A ~= 0));
nzmax = max(A(A ~= 0));
Note that if you have float data, you might want to consider values 'near' zero:
ztol = eps(max(A(:)));
nz = A < -ztol | A > ztol; % select non-zeros
nzmin = min(A(nz));
nzmax = max(A(nz));
It's refreshing to use a proliferation of 'nz', since it's my nationality =)