Re: [Help-gsl] Vector transposition

[Thomas Weber]

Hi Till,

I am sending this to the list (you replied to me only).


> i would need it to compute a generalized cross validation algorithm, 
> actually there's a step in the procedure where i need to do x^T A x, 
okay, so you need a scalar product (or dot product) with a matrix A,
namely <x, A*x>

y = A*x can be done with
gsl_blas_dgemv(CblasNoTrans, 1.0, A, x, 0.0, y)

<x, y> can then be done with
gsl_blas_ddot (x,y, &result)

where result is a double variable and everything involved is also of
double type.

The relevant chapter in the manual is 
12.  GSL BLAS Interface

Regards
        Thomas