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Subject: nonnegative Ax=b lsq for large, sparse A.
Date: Fri, 26 Jun 2009 13:31:01 +0000 (UTC)
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Hello all,

I have a large, sparse, rectangular (overdetermined) matrix A.

I'm solving Ax = b, where all elements of A, x and b are nonnegative.

I thought at first that lsqnonneg would be my ideal function, however, I hadn't realised that it is not useful for large sparse matrices (creates a full matrix the same size as A).

Does anyone know of an alternative for lsqnonneg which may be used with a large, sparse coefficients matrix?

A sample of the problem (.mat file containing A and b) can be found in:
http://www2.eng.cam.ac.uk/~thc29/lsqnonneg_sparse/

Tim Davis, if you happen across this, you may enjoy the sparsity pattern (it's for a tomographic reconstruction of a particle field in fluid flow).

Thanks all, and kind regards

Tom Clark