# ifndef CPPAD_CORE_ATOMIC_FOUR_DEVEL_JAC_SPARSITY_HPP
# define CPPAD_CORE_ATOMIC_FOUR_DEVEL_JAC_SPARSITY_HPP
// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-or-later
// SPDX-FileCopyrightText: Bradley M. Bell <bradbell@seanet.com>
// SPDX-FileContributor: 2003-24 Bradley M. Bell
// ----------------------------------------------------------------------------

namespace CppAD { // BEGIN_CPPAD_NAMESPACE

/*
------------------------------------------------------------------------------
{xrst_begin atomic_four_for_jac_sparsity dev}

Link from Forward Jacobian Sparsity Sweep to atomic_four Callback
#################################################################

Prototype
*********
{xrst_literal
   // BEGIN_FOR_JAC_SPARSITY
   // END_FOR_JAC_SPARSITY
}

InternalSparsity
****************
is the type used for internal sparsity calculations; i.e.,
sparse_pack or sparse_list.

call_id
*******
see :ref:`atomic_four_call@call_id` .

dependency
**********
if true, calculate dependency pattern,
otherwise calculate sparsity pattern.

ident_zero_x
************
This argument has size equal to the number of arguments to this
atomic function; i.e. the size of *ax* .
If *ident_zero_x* [ *j* ] is true, the argument *ax* [ *j* ]
is a constant parameter that is identically zero.

x_index
*******
is the variable index, on the tape, for the arguments to this atomic function.
This size of x_index is, the number of arguments to this atomic function.
The index zero is used for parameters.

y_index
*******
is the variable index, on the tape, for the results for this atomic function.
This size of y_index is m, the number of results for this atomic function.
The index zero is used for parameters.

var_sparsity
************
On input, for j = 0, ... , n-1, the sparsity pattern with index x_index[j],
is the sparsity for the j-th argument to this atomic function.
On output, for i = 0, ... , m-1, the sparsity pattern with index y_index[i],
is the sparsity for the i-th result for this atomic function.

Return Value
************
is true if the computation succeeds.

{xrst_end atomic_four_for_jac_sparsity}
*/
// BEGIN_FOR_JAC_SPARSITY
template <class Base>
template <class InternalSparsity>
bool atomic_four<Base>::for_jac_sparsity(
   size_t                           call_id      ,
   bool                             dependency   ,
   const vector<bool>&              ident_zero_x ,
   const vector<size_t>&            x_index      ,
   const vector<size_t>&            y_index      ,
   InternalSparsity&                var_sparsity )
// END_FOR_JAC_SPARSITY
{  typedef typename InternalSparsity::const_iterator iterator;

   // number of arguments and results for this atomic function
   size_t n = x_index.size();
   size_t m = y_index.size();

   // select_y
   vector<bool> select_y(m);
   for(size_t i = 0; i < m; ++i)
      select_y[i] = y_index[i] != 0;

   // determine select_x
   vector<bool> select_x(n);
   for(size_t j = 0; j < n; ++j)
   {  if( x_index[j] == 0 )
         select_x[j] = false;
      else
      {  // check if x_j depends on any previous variable
         iterator itr(var_sparsity, x_index[j]);
         size_t ell = *itr;
         select_x[j] = ell < var_sparsity.end();
      }
   }
   sparse_rc< vector<size_t> > pattern_out;
   bool ok = jac_sparsity( call_id,
      dependency, ident_zero_x, select_x, select_y, pattern_out
   );
   if( ! ok ) ok = jac_sparsity(
      call_id, dependency, select_x, select_y, pattern_out
   );
   if( ! ok )
      return false;
   //
   // transfer sparsity patterns from pattern_out to var_sparsity
   size_t                nnz = pattern_out.nnz();
   const vector<size_t>& row( pattern_out.row() );
   const vector<size_t>& col( pattern_out.col() );
   for(size_t k = 0; k < nnz; ++k)
   {  size_t i = row[k];
      size_t j = col[k];
      CPPAD_ASSERT_KNOWN(
         select_y[i] && select_x[j],
         "atomic: jac_sparsity: pattern_out not in "
         "select_x or select_y range"
      );
      iterator itr(var_sparsity, x_index[j]);
      size_t ell = *itr;
      while( ell < var_sparsity.end() )
      {  var_sparsity.post_element( y_index[i], ell );
         ell = *(++itr);
      }
   }
   for(size_t i = 0; i < m; ++i)
      var_sparsity.process_post( y_index[i] );
   //
   return true;
}

/*
------------------------------------------------------------------------------
{xrst_begin atomic_four_rev_jac_sparsity dev}

Link from Reverse Jacobian Sparsity Sweep to atomic_four Callback
#################################################################

Prototype
*********
{xrst_literal
   // BEGIN_REV_JAC_SPARSITY
   // END_REV_JAC_SPARSITY
}

InternalSparsity
****************
Is the type used for internal sparsity calculations; i.e.,
sparse_pack or sparse_list.

call_id
*******
see :ref:`atomic_four_call@call_id`

dependency
**********
if true, calculate dependency pattern,
otherwise calculate sparsity pattern.

ident_zero_x
************
This argument has size equal to the number of arguments to this
atomic function; i.e. the size of *ax* .
If *ident_zero_x* [ *j* ] is true, the argument *ax* [ *j* ]
is a constant parameter that is identically zero.

x_index
*******
is the variable index, on the tape, for the arguments to this atomic function.
This size of x_index is n, the number of arguments to this atomic function.
The index zero is used for parameters.

y_index
*******
is the variable index, on the tape, for the results for this atomic function.
This size of y_index is m, the number of results for this atomic function.
The index zero is used for parameters.

var_sparsity
************
We are given a sparsity pattern an outer function G(y, x) and compute
the pattern for an inner function H(x), which is the outer functions
with the components of y treated as functions of x; i.e.
H(x) = G( Y(x), x).

y_index
=======
On input, for i = 0, ... , m-1, the sparsity pattern with index y_index[i],
is the sparsity of the outer function with respect to the i-th
result for this atomic function.

x_index
=======
On input, for j = 0, ... , n-1, the sparsity pattern with index x_index[j],
is the sparsity for the outer function with respect to the j-th
argument to this atomic function.
On output, for j = 0, ... , n-1, the sparsity pattern with index x_index[j],
is the sparsity for the inner function with respect to the j-th
argument to this atomic function.

Return Value
************
is true if the computation succeeds.

{xrst_end atomic_four_rev_jac_sparsity}
*/
// BEGIN_REV_JAC_SPARSITY
template <class Base>
template <class InternalSparsity>
bool atomic_four<Base>::rev_jac_sparsity(
   size_t                           call_id      ,
   bool                             dependency   ,
   const vector<bool>&              ident_zero_x ,
   const vector<size_t>&            x_index      ,
   const vector<size_t>&            y_index      ,
   InternalSparsity&                var_sparsity )
// END_REV_JAC_SPARSITY
{  typedef typename InternalSparsity::const_iterator iterator;

   // number of arguments and results for this atomic function
   size_t n = x_index.size();
   size_t m = y_index.size();

   // selection vectors
   vector<bool> select_x(n), select_y(m);

   // select_x
   for(size_t j = 0; j < n; ++j)
      select_x[j] = x_index[j] != 0;

   // determine select_y
   for(size_t i = 0; i < m; ++i)
   {  if( y_index[i] == 0 )
         select_y[i] = false;
      else
      {  // check if y_i has sparsity is non-empty
         iterator itr(var_sparsity, y_index[i]);
         size_t ell = *itr;
         select_y[i] = ell < var_sparsity.end();
      }
   }
   sparse_rc< vector<size_t> > pattern_out;
   bool ok = jac_sparsity( call_id,
      dependency, ident_zero_x, select_x, select_y, pattern_out
   );
   if( ! ok ) ok = jac_sparsity(
      call_id, dependency, select_x, select_y, pattern_out
   );
   if( ! ok )
      return false;
   //
   // transfer sparsity patterns from pattern_out to var_sparsity
   size_t                nnz = pattern_out.nnz();
   const vector<size_t>& row( pattern_out.row() );
   const vector<size_t>& col( pattern_out.col() );
   for(size_t k = 0; k < nnz; ++k)
   {  size_t i = row[k];
      size_t j = col[k];
      CPPAD_ASSERT_KNOWN(
         select_y[i] && select_x[j],
         "atomic: jac_sparsity: pattern_out not in "
         "select_x or select_y range"
      );
      iterator itr(var_sparsity, y_index[i]);
      size_t ell = *itr;
      while( ell < var_sparsity.end() )
      {  var_sparsity.post_element( x_index[j], ell );
         ell = *(++itr);
      }
   }
   for(size_t j = 0; j < n; ++j)
      var_sparsity.process_post( x_index[j] );
   //
   return true;
}

} // END_CPPAD_NAMESPACE
# endif
