Re: [Boost-users] Multiplying a matrix and vector ===> vector

29 Oct 2012

      That worked but only with a boost::ublas::numeric::compressed_vector and 
not a simple boost::ublas::numeric::vector.

Thanks,
Vipin

On Sun, 28 Oct 2012, Oswin Krause wrote:
...
Hi,
without knowing what CLN should be (would have been nice to know beforehand, 
that you are using an unusual value_typ for vectors/matrics...)
I suspect you are compiling in debug mode and the error goes away in release. 
This is because the debug test for numeric stability fails.
Try to define this before including anything from ublas (or set as compile 
flag):
BOOST_UBLAS_TYPE_CHECK=0
On 2012-10-27 11:47, Vipin Varma wrote:
...
Yes, in fact I just realised that I can do all the usual algebra for
standard data types like double, float etc. But when I try to use CLN
rational numbers - which is what I want - the below step fails with
the following compile error:
<ERROR>
/usr/include/boost/numeric/ublas/traits.hpp:97: error: no matching
function for call to 'sqrt(const cln::cl_RA&)'
/usr/include/bits/mathcalls.h:157: note: candidates are: double 
sqrt(double)
/usr/include/c++/4.3/cmath:434: note:                 long double
std::sqrt(long double)
/usr/include/c++/4.3/cmath:430: note:                 float 
std::sqrt(float)
<ERROR>
However I can still multiply a scalar CLN number with a CLN matrix
and assign it to a new CLN matrix; it's multiplication of a CLN vector
with a CLN matrix that gives the problem.
Thanks,
Vipin
On Fri, 26 Oct 2012, Oswin Krause wrote:
...
Have you tried:
vector z = prod(m,x);
On 2012-10-26 13:08, Vipin Varma wrote:
...
Dear all,
My basic requirement is to multiply a matrix and a vector and then to
store it into a vector using Boost's UBLAS.
When I multiply a boost::numeric::ublas::compressed_matrix with a
boost::numeric::ublas::vector using prod(matrix, vector), the output
is a boost::numeric::ublas::matrix_vector_binary1. E.g.
<PSEUDOCODE>
boost::numeric::ublas::compressed_matrix m;
boost::numeric::ublas::vector x;
boost::numeric::ublas::matrix_vector_binary1
...
tmp;
tmp = prod(m,x);
<PSEUDOCODE>
The problem is that in the third field --- which expects the
operation type --- in line 3, I do not know what to enter or how to
specify the type of operation; I tried '*' and 'prod' and 'vector' and
'compressed_matrix' but none work.
Alternatively, I can avoid the tmp variable altogether and get a
working program to copy the result of matrix-vector multiplication
onto a new vector y but then I would need two multiplications. E.g.
<CODE>
std::copy(prod(m,x).begin(), prod(m,x).end(), y.begin());
<CODE>
Any suggestions on how to declare a matrix_vector_binary1 correctly
or how to get the finaly result efficiently onto a vector will be
appreciated.
Regards,
Vipin

Boost-users mailing list
Boost-users@lists.boost.org
http://lists.boost.org/mailman/listinfo.cgi/boost-users
_______________________________________________
Boost-users mailing list
Boost-users@lists.boost.org
http://lists.boost.org/mailman/listinfo.cgi/boost-users
_______________________________________________
Boost-users mailing list
Boost-users@lists.boost.org
http://lists.boost.org/mailman/listinfo.cgi/boost-users
_______________________________________________
Boost-users mailing list
Boost-users@lists.boost.org
http://lists.boost.org/mailman/listinfo.cgi/boost-users