Extract non-zero elements from matrix with double precision numbers

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Peter
Peter on 15 May 2013
How can I extract all of the non-zero number from a matrix? I tried using the function nonzero(M), but since the values in the matrix are all decimals, I got the error "Undefined function 'nonzero' for input arguments of type 'double' ".
I just wand a row vector (or column vector, or whatever is easiest) of all non-zero elements. Obviously I can just loop through each element, but this is insanely inefficient.

Accepted Answer

Azzi Abdelmalek
Azzi Abdelmalek on 15 May 2013
out=M(M~=0)

More Answers (1)

Matt Kindig
Matt Kindig on 15 May 2013
Edited: Matt Kindig on 15 May 2013
notZeros= M(M~=0);
Keep in mind that due to numerical precision, some of your matrix elements may be small but not identically zero. You might want to use some sort of tolerance instead, such as:
notZeros = M(abs(M)<10*eps); %for example

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