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Subject: Re: Indexing into large sparse matrix
Date: Tue, 24 Mar 2009 22:46:01 +0000 (UTC)
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"NIcholas" <remove.this_nmg33@cornell.edu> wrote in message <gqbn11$9c2$1@fred.mathworks.com>...
> The application is a "sparse image" filtering.  I have a large set of grid points with weights (intensities) and I am trying to filter this image with a gaussian and I am only interested in the value at non-zero locations in the original image - 
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If A represents the original image, then all this would require is

>>PDF(A~=0)