Re: [Help-gsl] Question on gsl_blas_strsm

[Brian Gough]

Johannes Wohlmuth wrote:
> Hello,
>
> I need some help with a Matrixproblem:
> I want to solve C= A/B! B is a symmetric and positive definite
> Matrix. I don't understand why there isn't any function like 
> gsl_blas_ssysm! gsl_blas_strsm uses only the upper or the lower 
> part of B? Is the following still the right function for my problem?
> gsl_blas_strsm (CblasRight, CblasUpper, CblasTrans, CblasNonUnit,1.0, B, A);

Hello,

The blas functions are part of a standard, so we just implement what is 
in the standard. You can use the Cholesky decomposition to convert a 
symmetric positive definite system to a triangular system.

> Another thing is: Why is there a difference when I use 
> the upper or the lower part of the matrix B, when that
> is symmetric?

If you still have this problem can you submit it as a bug report with an 
example program to address@hidden Thanks.

--
best regards,

Brian Gough
(GSL Maintainer)

Network Theory Ltd,
Publishing the GSL Manual - http://www.network-theory.co.uk/gsl/manual/