// 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
// ----------------------------------------------------------------------------


# include <cppad/cppad.hpp>

bool sparse_vec_ad(void)
{  bool ok = true;
   using namespace CppAD;

   // dimension of the domain space
   size_t n = 3;

   size_t i, j;

   // independent variable vector
   CPPAD_TESTVECTOR(AD<double>) X(n);
   for(j = 0; j < n; j++)
      X[j] = AD<double>(j);
   Independent(X);

   // dependent variable vector
   size_t m = n;
   CPPAD_TESTVECTOR(AD<double>) Y(m);

   // check results vector
   CPPAD_TESTVECTOR( bool )  Check(m * n);

   // Create a VecAD so that there are two in the tape and the sparsity
   // pattern depends on the second one (checks addressing VecAD objects)
   VecAD<double> W(n);

   // VecAD equal to X
   VecAD<double> Z(n);
   AD<double> J;
   for(j = 0; j < n; j++)
   {  J    = AD<double>(j);
      W[J] = X[0];
      Z[J] = X[j];

      // y[i] depends on x[j] for j <= i
      // (and is non-linear for j <= 1).
      if( j == 1 )
         Y[j] = Z[J] * Z[J];
      else
         Y[j] = Z[J];
   }

   // compute dependent variables values
   AD<double> P = 1;
   J = AD<double>(0);
   for(j = 0; j < n; j++)
   {  for(i = 0; i < m; i++)
         Check[ i * m + j ] = (j <= i);
   }

   // create function object F : X -> Y
   ADFun<double> F(X, Y);

   // dependency matrix for the identity function W(x) = x
   CPPAD_TESTVECTOR( bool ) Identity(n * n);
   for(i = 0; i < n; i++)
   {  for(j = 0; j < n; j++)
         Identity[ i * n + j ] = false;
      Identity[ i * n + i ] = true;
   }
   // evaluate the dependency matrix for Identity(F(x))
   CPPAD_TESTVECTOR( bool ) Px(m * n);
   Px = F.RevSparseJac(n, Identity);

   // check values
   for(i = 0; i < m; i++)
   {  for(j = 0; j < n; j++)
         ok &= (Px[i * m + j] == Check[i * m + j]);
   }

   // evaluate the dependency matrix for F(Identity(x))
   CPPAD_TESTVECTOR( bool ) Py(m * n);
   Py = F.ForSparseJac(n, Identity);

   // check values
   for(i = 0; i < m; i++)
   {  for(j = 0; j < n; j++)
         ok &= (Py[i * m + j] == Check[i * m + j]);
   }

   // test sparsity pattern for Hessian of F_2 ( Identity(x) )
   CPPAD_TESTVECTOR(bool) Hy(m);
   for(i = 0; i < m; i++)
      Hy[i] = false;
   Hy[2] = true;
   CPPAD_TESTVECTOR(bool) Pxx(n * n);
   Pxx = F.RevSparseHes(n, Hy);
   for(i = 0; i < n; i++)
   {  for(j = 0; j < n; j++)
         ok &= (Pxx[i * n + j] == false );
   }

   // test sparsity pattern for Hessian of F_1 ( Identity(x) )
   for(i = 0; i < m; i++)
      Hy[i] = false;
   Hy[1] = true;
   Pxx = F.RevSparseHes(n, Hy);
   for(i = 0; i < n; i++)
   {  for(j = 0; j < n; j++)
         ok &= (Pxx[i * n + j] == ( (i <= 1) && (j <= 1) ) );
   }


   return ok;
}
