I apologise for the error in the original message, please see the
corrected version below.
Cheers for help
Will
-------- Original Message --------
Message-ID: <[EMAIL PROTECTED]>
Date: Fri, 31 Aug 2007 13:05:18 +0100
From: William Astle <[EMAIL PROTECTED]>
User-Agent: Thunderbird 2.0.0.5 (X11/20070724)
MIME-Version: 1.0
To: [email protected]
Subject: gsl_linalg_householder_mh question
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Hi,
I wonder if someone could explain to me why the following program gives
output
0.000000 -3.000000 -5.000000
-3.000000 -8.000000 -15.000000
-5.000000 -15.000000 -24.000000
from the definition of the Householder transformation used in the gsl
manual, with tau=1.0 and v=(2.0, 3.0, 5.0) I would expect
-3.000000 -6.000000 -10.000000
-6.000000 -8.000000 -15.000000
-10.000000 -15.000000 -24.000000
it seems like gsl_linalg_householder_mh forces v(0)=1.0 is this
correct? I guess there is no loss of generality but it seems odd, could
some one explain to me?
__________________________
#include <gsl/gsl_matrix.h>
#include <gsl/gsl_linalg.h>
#include <stdio.h>
int main()
{
gsl_vector* pgslvec;
gsl_matrix* pgslmat;
double tau=1.0;
int i, j;
pgslmat=gsl_matrix_alloc(3,3);
pgslvec=gsl_vector_alloc(3);
gsl_matrix_set_identity(pgslmat);
gsl_vector_set(pgslvec, 0, 2.0);
gsl_vector_set(pgslvec, 1, 3.0);
gsl_vector_set(pgslvec, 2, 5.0);
gsl_linalg_householder_mh(tau,pgslvec, pgslmat);
for(i=0;i<3;i++)
{
printf("\n");
for(j=0;j<3;j++)
printf("%f\t",(float) gsl_matrix_get(pgslmat, i, j));
}
gsl_vector_free(pgslvec);
gsl_matrix_free(pgslmat);
return 0;
}
_______________________________________________
Help-gsl mailing list
[email protected]
http://lists.gnu.org/mailman/listinfo/help-gsl
