Test every element in matrix

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Leor Greenberger 2011-9-19

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I have an M x N matrix, where I want to test whether each element is greater than some constant a, and if it is, perform some arithmetic to it. The only way I can think of doing this is using 2 For loops nested to select each element and an If statement to perform checking. Is this the best I can do?

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采纳的回答

Tigersnooze 2011-9-19

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You can say something like this, instead of using a loop (assuming the matrix is called A):

A(A > a) = A(A > a) + arithmetic.

"Vectorizing" like this won't have significant speed advantages with smaller matrices, but when the matrix gets bigger you'll see huge time savings. Just a heads up for the future.