Failed to determine the cause of the error "no match for" operator <'"

Question

I am using CodeSourcery implementation of the vector signal processing library ( vsipl ++ ). I wrote a function that should return [I + a * A] ^ - 1 B, where I am the identity matrix, and A and B are compatible square matrices as follows:

namespace vsipl {

template< class T1, class T2, class O1, class O2, class L1, class L2,
     template< dimension_type, class, class, class > class B1,
     template< dimension_type, class, class, class > class B2 >
Matrix< typename Promotion< T1, T2 >::type, 
        B1< 2, typename Promotion< T1, T2 >::type, O1, L1 > > 
inv_mult( typename Promotion< T1, T2 >::type a, 
       Matrix< T1, B1< 2, T1, O1, L1 > > const& A,
       Matrix< T2, B2< 2, T2, O2, L2 > > const& B
     ) 
{
 typedef typename Promotion< T1, T2 >::type value_type;
 typedef Matrix< value_type, B1< 2, value_type, O1, L1 > > ret_type;
 typedef lud< value_type, by_reference > lud_type;

 ret_type ret(A.size(0),A.size(1),0), denom(A.size(0),A.size(1),0);

 //I + a*A
 denom.diag() = 1;
 denom = denom + a*A;

 lud_type ld( denom.size() );
 ld.decompose( denom );

 //as a side effect of using LAPACK as a back end, this requires a template
 //param to indicate precisely what is being solved.
 ld.solve< mat_ntrans >( B, ret );  // <--- Line generating error.

 return ret;
}//inv_mult
}//vsipl

To be clear, vsipl ++ Matrices accepts two parameters: a type and a block that describes how information is stored. This block is the cause of the soup pattern above. In addition, the object lud splits LU into a matrix A and then solves Ax = b using the decomposed form A.

When I try to compile this with gcc (both 4.2.1 on MacOs 10.6 and 4.3.0 on Fedora 9), I get the following error

error: no match for 'operator<' in 'ld.vsip::lud<T, by_reference>::solve [with 
 vsip::mat_op_type tr = tr, Block0 = Block0, Block1 = Block1, T = double] < mat_ntrans

, Promotion, , .

?

Answer 1

ld.template solve< mat_ntrans >

,