Path: news.mathworks.com!not-for-mail From: <HIDDEN> Newsgroups: comp.soft-sys.matlab Subject: Re: Matrix Multiplication Date: Wed, 11 May 2011 22:42:04 +0000 (UTC) Organization: Boeing Co Lines: 17 Message-ID: <iqf3bs$lqc$1@newscl01ah.mathworks.com> References: <iqevjs$cb2$1@newscl01ah.mathworks.com> Reply-To: <HIDDEN> NNTP-Posting-Host: www-06-blr.mathworks.com Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Trace: newscl01ah.mathworks.com 1305153724 22348 172.30.248.38 (11 May 2011 22:42:04 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Wed, 11 May 2011 22:42:04 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 756104 Xref: news.mathworks.com comp.soft-sys.matlab:726279 "Vineet " <yadavvineet@gmail.com> wrote in message <iqevjs$cb2$1@newscl01ah.mathworks.com>... > Is there a way in Matlab to specify that the product (matrix multiplication) of two matrices would be symmetric so that matrix multiplication happens faster. For ex: > A*A' > or > matrix multiplication of two symmetric matrices > > I know there are routines to do it in BLAS : > like: SSYMM, DSYMM, CHEMM, CSYMM, ZHEMM, ZSYMM (to multiply two symmetric matrix) > or > SSYRK, DSYRK, CHERK, CSYRK, ZHERK, ZSYRK (to multiply matrix by its adjoint) > > Thanks > Vineet MATLAB does this automatically if you do the matrix multiply in a form that it recognizes. e.g., in your A*A' above the dgemm routine will not be called. Rather, one of the BLAS symmetric routines will be called and then the other triangular part is filled in with just a copy of the traingular part that was calculated in the BLAS routine. James Tursa