On Sun 11 Feb 07, 8:43 AM, John D Lamb <[EMAIL PROTECTED]> said:
> On Sun, 2007-02-11 at 02:28 -0500, Peter Jay Salzman wrote:
> > Just discovered GSL a few hours ago. Very neat!
>
> > I've been trying to figure out how to multiply a vector and matrix. How is
> > one supposed to compute something like
> >
> > A x
> >
> > given a gsl_matrix A and a gsl_vector x? Does x need to be defined as a
> > nx1 gsl_matrix for a column vector and a 1xn gsl_matrix for a row vector?
>
> Look at the documentation for gsl_blas_dgemv. The vector x should be a
> gsl_vector and the result a vector y. Vectors and matrices are passed as
> pointers. You should end up with something like
>
> #include<gsl/gsl_blas.h>
> ...
>
> err = gsl_blas_dgemv( CblasNoTrans, 1.0, A, x, 0.0, y );
Thanks, John!
gsl_blas_dgemv?!? Holy smokes! No wonder I had a hard time finding it.
Has anyone thought of renaming this function something like
"gsl_matrix_multiply()"?
:-P
Thanks again! :) Judging by that name, I may have a lot of Googling ahead
of me tonight!
Pete
--
How VBA rounds a number depends on the number's internal representation.
You cannot always predict how it will round when the rounding digit is 5.
If you want a rounding function that rounds according to predictable rules,
you should write your own.
-- MSDN, on Microsoft VBA's "stochastic" rounding function
Peter Jay Salzman, email: [EMAIL PROTECTED] web: http://www.dirac.org/p
PGP Fingerprint: B9F1 6CF3 47C4 7CD8 D33E 70A9 A3B9 1945 67EA 951D
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