MATLAB: Sum a column depending on another column

MATLABsum column criteria

Hi there,
I would like to sum values in a column where a criterion has been met in another column in a corresponding row of a matrix.
take the matrix:
xx  6  xx  1;
xx  9  xx  0;
xx  10 xx  1;
I want to sum the second column but only for rows where the fourth column is equal to one.
Hence, using the example, I would hope to have a solution of 16.
Any help with this simple problem is greatly appreciated.
James

Best Answer

out = sum(A(A(:,4)~=0,2))
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