Does Matlab use a QR or LU decomposition when solving a matrix equation?
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When Matlab computes A\B or A\b does it first compute the LU decomposition of A or the QR decomposition? I'm having accuracy issues and trying to compare my answers to those I get in C using LAPACK.
Thanks very much.
David
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Honglei Chen
el 16 de Jul. de 2012
There are actually some information regarding you question in the documentation
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Paul Metcalf
el 16 de Jul. de 2012
Editada: Paul Metcalf
el 16 de Jul. de 2012
I don't know the answer to your question, but you will need to provide more details to get a proper response to your question. For example:
- Is your matrix A square?
- What is the size/order of A?
- When using C/LAPACK, what data types have you cast for A?
- Are your results only slightly different or dramatically different?
MATLAB using DOUBLE arithmetic for all internal operations. If you are not using real64 types in C, then you might be accumulating quantisation errors...
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Paul Metcalf
el 18 de Jul. de 2012
Glad you got it sorted. Out of curiosity, how long does your solution take?
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