Re: [ublas] svd example program

From: Kresimir Fresl (fresl_at_[hidden])
Date: 2005-05-27 01:23:29

Hi Jack,

you wrote:

> I use g++ an got a bunch of errors. I think I m not including proper
> libs or I m not linking the correct libs. Any help is appreciated.

> #include <iostream>
> #include <boost/numeric/bindings/lapack/gesdd.hpp>
> #include<boost/numeric/bindings/traits/ublas_matrix.hpp>
> #include<boost/numeric/bindings/traits/ublas_vector.hpp>
> #include <boost/numeric/ublas/matrix.hpp>
> #include <boost/numeric/ublas/vector.hpp>
> #include "printmatrix.hpp"
> 
> using namespace boost::numeric::bindings::lapack;
> using namespace boost::numeric::ublas;
> // using namespace std;
> using namespace print;
> int main () {
> 
>  matrix<double> A (4,2);

To use Lapack routines your matrices must be column major:

     matrix<double, column_major> A (4,2);

>  A(0,0)=2;
>  A(0,1)=4;
>  A(1,0)=1;
>  A(1,1)=3;
>  A(2,0)=0;
>  A(2,1)=0;
>  A(3,0)=0;
>  A(3,1)=0;
>  print_matrix(A);
> 
>  matrix<double> U(4,4);
>  matrix<double> V(2,2);

     matrix<double, column_major> U (4,4);
     matrix<double, column_major> V (2,2);

>  vector<double> S(8);
>  gesdd(&A,&S,&U,&V);

There's no need for dereferencing (bindings do it for you ;o):

     gesdd (A, S, U, V);

> //   print_matrix(S);
> //   print_matrix(U);
> //   print_matrix(V);
> 
>  return 0;
> }

For more info see examples in

     http://tinyurl.com/ccmwa

and docs in

     http://tinyurl.com/6acht

(BTW, I didn't update ublas and bindings on my machine for
some time. I think that in the meantime interface of ublas
slightly changed, so there may be some more errors, but I
hope that this helps.)

Regards,

fres