atomic_four_mat_mul_hes_sparsity.hpp

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Atomic Matrix Multiply Jacobian Sparsity Pattern: Example Implementation

Purpose

The hes_sparsity routine overrides the virtual functions used by the atomic_four base class for Jacobian sparsity calculations; see hes_sparsity .

Example

The file atomic_four_mat_mul_sparsity.cpp contains an example and test using this operator.

Source

# include <cppad/example/atomic_four/mat_mul/mat_mul.hpp>

namespace CppAD { // BEGIN_CPPAD_NAMESPACE
//
// hes_sparsity override
template <class Base>
bool atomic_mat_mul<Base>::hes_sparsity(
   size_t                                         call_id      ,
   const CppAD::vector<bool>&                     ident_zero_x ,
   const CppAD::vector<bool>&                     select_x     ,
   const CppAD::vector<bool>&                     select_y     ,
   CppAD::sparse_rc< CppAD::vector<size_t> >&     pattern_out  )
{
   // n_left, n_middle, n_right
   size_t n_left, n_middle, n_right;
   get(call_id, n_left, n_middle, n_right);
   //
   // n
   size_t n     = select_x.size();
   //
   // check sizes
# ifndef NDEBUG
   size_t m     = select_y.size();
   assert( n == n_middle * ( n_left +  n_right ) );
   assert( m == n_left * n_right );
# endif
   //
   // offset
   size_t offset = n_left * n_middle;
   //
   // pattern_out
   pattern_out.resize(n, n, 0);
   for(size_t i = 0; i < n_left; ++i)
   {  for(size_t j = 0; j < n_right; ++j)
      {  size_t ij = i * n_right + j;               // C_{i,j} = y[ij]
         if( select_y[ij] ) for(size_t k = 0; k < n_middle; ++k)
         {  size_t ik = i * n_middle + k;          // A_{i,k} = x[ik]
            size_t kj = offset + k * n_right + j;  // B_{k,j} = x[kj]
            if( select_x[ik] && select_x[kj] )
            {  // an (ik, kj) pair can only occur once in this loop
               pattern_out.push_back(ik, kj);
               pattern_out.push_back(kj, ik);
            }
         }
      }
   }
# ifndef NDEBUG
   // sorting checks hat there are no duplicate entries
   pattern_out.row_major();
# endif
   //
   return true;
}
} // END_CPPAD_NAMESPACE