find sum of all the entries with value 0
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I have a cell matrix of mat = [ 1 0 0 4;0 2 0 4], i want to find the sum of the all the entries having value 0. in the case of given example the entries having count 0 are 4; so sum will be 4. how can i do this.
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Jos (10584)
le 30 Nov 2013
NNZ is the dedicated function to do this:
nnz(~mat)
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John D'Errico
le 30 Nov 2013
Note that nnz(~mat) will be poor even for large sparse matrices, because if mat is sparse, then ~mat must create a large and rather dense logical matrix. Better then would be to use a form like:
numel(mat) - nnz(mat)
In my tests, for a large fairly sparse matrix like that generated by Matt in his comment, my form was the fastest.
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