Prev Next old_usead_1.cpp

@(@\newcommand{\W}[1]{ \; #1 \; } \newcommand{\R}[1]{ {\rm #1} } \newcommand{\B}[1]{ {\bf #1} } \newcommand{\D}[2]{ \frac{\partial #1}{\partial #2} } \newcommand{\DD}[3]{ \frac{\partial^2 #1}{\partial #2 \partial #3} } \newcommand{\Dpow}[2]{ \frac{\partial^{#1}}{\partial {#2}^{#1}} } \newcommand{\dpow}[2]{ \frac{ {\rm d}^{#1}}{{\rm d}\, {#2}^{#1}} }@)@
Using AD to Compute Atomic Function Derivatives

Deprecated 2013-05-27
This example has been deprecated because it is easier to use the checkpoint class instead.

Purpose
Consider the case where an inner function is used repeatedly in the definition of an outer function. In this case, it may reduce the number of variables size_var , and hence the required memory.

Simple Case
This example is the same as old_reciprocal.cpp , except that it uses AD to compute the derivatives needed by an atomic function. This is a simple example of an inner function, and hence not really useful for the purpose above; see old_usead_2.cpp for a more complete example.
# include <cppad/cppad.hpp>

namespace { // Begin empty namespace
     using CppAD::AD;
     using CppAD::ADFun;
     using CppAD::vector;

     // ----------------------------------------------------------------------
     // function that computes reciprocal
     ADFun<double>* r_ptr_;
     void create_r(void)
     {     vector< AD<double> > ax(1), ay(1);
          ax[0]  = 1;
          CppAD::Independent(ax);
          ay[0]  = 1.0 / ax[0];
          r_ptr_ = new ADFun<double>(ax, ay);
     }
     void destroy_r(void)
     {     delete r_ptr_;
          r_ptr_ = CPPAD_NULL;
     }

     // ----------------------------------------------------------------------
     // forward mode routine called by CppAD
     bool reciprocal_forward(
          size_t                   id ,
          size_t                    k ,
          size_t                    n ,
          size_t                    m ,
          const vector<bool>&      vx ,
          vector<bool>&            vy ,
          const vector<double>&    tx ,
          vector<double>&          ty
     )
     {     assert( id == 0 );
          assert( n == 1 );
          assert( m == 1 );
          assert( k == 0 || vx.size() == 0 );
          bool ok = true;
          vector<double> x_q(1), y_q(1);

          // check for special case
          if( vx.size() > 0 )
               vy[0] = vx[0];

          // make sure r_ has proper lower order Taylor coefficients stored
          // then compute ty[k]
          for(size_t q = 0; q <= k; q++)
          {     x_q[0] = tx[q];
               y_q    = r_ptr_->Forward(q, x_q);
               if( q == k )
                    ty[k] = y_q[0];
               assert( q == k || ty[q] == y_q[0] );
          }
          return ok;
     }
     // ----------------------------------------------------------------------
     // reverse mode routine called by CppAD
     bool reciprocal_reverse(
          size_t                   id ,
          size_t                    k ,
          size_t                    n ,
          size_t                    m ,
          const vector<double>&    tx ,
          const vector<double>&    ty ,
          vector<double>&          px ,
          const vector<double>&    py
     )
     {     assert( id == 0 );
          assert( n == 1 );
          assert( m == 1 );
          bool ok = true;
          vector<double> x_q(1), w(k+1), dw(k+1);

          // make sure r_ has proper forward mode coefficients
          size_t q;
          for(q = 0; q <= k; q++)
          {     x_q[0] = tx[q];
# ifdef NDEBUG
               r_ptr_->Forward(q, x_q);
# else
               vector<double> y_q(1);
               y_q    = r_ptr_->Forward(q, x_q);
               assert( ty[q] == y_q[0] );
# endif
          }
          for(q = 0; q <=k; q++)
               w[q] = py[q];
          dw = r_ptr_->Reverse(k+1, w);
          for(q = 0; q <=k; q++)
               px[q] = dw[q];

          return ok;
     }
     // ----------------------------------------------------------------------
     // forward Jacobian sparsity routine called by CppAD
     bool reciprocal_for_jac_sparse(
          size_t                               id ,
          size_t                                n ,
          size_t                                m ,
          size_t                                p ,
          const vector< std::set<size_t> >&     r ,
          vector< std::set<size_t> >&           s )
     {     assert( id == 0 );
          assert( n == 1 );
          assert( m == 1 );
          bool ok = true;

          vector< std::set<size_t> > R(1), S(1);
          R[0] = r[0];
          S = r_ptr_->ForSparseJac(p, R);
          s[0] = S[0];

          return ok;
     }
     // ----------------------------------------------------------------------
     // reverse Jacobian sparsity routine called by CppAD
     bool reciprocal_rev_jac_sparse(
          size_t                               id ,
          size_t                                n ,
          size_t                                m ,
          size_t                                p ,
          vector< std::set<size_t> >&           r ,
          const vector< std::set<size_t> >&     s )
     {
          assert( id == 0 );
          assert( n == 1 );
          assert( m == 1 );
          bool ok = true;

          vector< std::set<size_t> > R(p), S(p);
          size_t q;
          for(q = 0; q < p; q++)
               S[q] = s[q];
          R = r_ptr_->RevSparseJac(p, S);
          for(q = 0; q < p; q++)
               r[q] = R[q];

          return ok;
     }
     // ----------------------------------------------------------------------
     // reverse Hessian sparsity routine called by CppAD
     bool reciprocal_rev_hes_sparse(
          size_t                               id ,
          size_t                                n ,
          size_t                                m ,
          size_t                                p ,
          const vector< std::set<size_t> >&     r ,
          const vector<bool>&                   s ,
          vector<bool>&                         t ,
          const vector< std::set<size_t> >&     u ,
          vector< std::set<size_t> >&           v )
     {     // Can just return false if not use RevSparseHes.
          assert( id == 0 );
          assert( n == 1 );
          assert( m == 1 );
          bool ok = true;

          // compute sparsity pattern for T(x) = S(x) * f'(x)
          vector<bool> T(1), S(1);
          S[0]   = s[0];
          T      = r_ptr_->RevSparseJac(1, S);
          t[0]   = T[0];

          // compute sparsity pattern for A(x) = U(x)^T * f'(x)
          vector<bool> Ut(p), A(p);
          size_t q;
          for(q = 0; q < p; q++)
               Ut[q] = false;
          std::set<size_t>::iterator itr;
          for(itr = u[0].begin(); itr != u[0].end(); itr++)
               Ut[*itr] = true;
          A = r_ptr_-> RevSparseJac(p, Ut);

          // compute sparsity pattern for H(x) = R^T * (S * F)''(x)
          vector<bool> H(p), R(n);
          for(q = 0; q < p; q++)
               R[q] = false;
          for(itr = r[0].begin(); itr != r[0].end(); itr++)
               R[*itr] = true;
          r_ptr_->ForSparseJac(p, R);
          H = r_ptr_->RevSparseHes(p, S);

          // compute sparsity pattern for V(x) = A(x)^T + H(x)^T
          v[0].clear();
          for(q = 0; q < p; q++)
               if( A[q] | H[q] )
                    v[0].insert(q);

          return ok;
     }
     // ---------------------------------------------------------------------
     // Declare the AD<double> routine reciprocal(id, ax, ay)
     CPPAD_USER_ATOMIC(
          reciprocal                 ,
          CppAD::vector              ,
          double                     ,
          reciprocal_forward         ,
          reciprocal_reverse         ,
          reciprocal_for_jac_sparse  ,
          reciprocal_rev_jac_sparse  ,
          reciprocal_rev_hes_sparse
     )
} // End empty namespace

bool old_usead_1(void)
{     bool ok = true;
     using CppAD::NearEqual;
     double eps = 10. * CppAD::numeric_limits<double>::epsilon();

     // --------------------------------------------------------------------
     // Create the ADFun<doulbe> r_
     create_r();

     // --------------------------------------------------------------------
     // Create the function f(x)
     //
     // domain space vector
     size_t n  = 1;
     double  x0 = 0.5;
     vector< AD<double> > ax(n);
     ax[0]     = x0;

     // declare independent variables and start tape recording
     CppAD::Independent(ax);

     // range space vector
     size_t m = 1;
     vector< AD<double> > ay(m);

     // call user function and store reciprocal(x) in au[0]
     vector< AD<double> > au(m);
     size_t id = 0;           // not used
     reciprocal(id, ax, au);     // u = 1 / x

     // call user function and store reciprocal(u) in ay[0]
     reciprocal(id, au, ay);     // y = 1 / u = x

     // create f: x -> y and stop tape recording
     ADFun<double> f;
     f.Dependent(ax, ay);  // f(x) = x

     // --------------------------------------------------------------------
     // Check function value results
     //
     // check function value
     double check = x0;
     ok &= NearEqual( Value(ay[0]) , check,  eps, eps);

     // check zero order forward mode
     size_t q;
     vector<double> x_q(n), y_q(m);
     q      = 0;
     x_q[0] = x0;
     y_q    = f.Forward(q, x_q);
     ok &= NearEqual(y_q[0] , check,  eps, eps);

     // check first order forward mode
     q      = 1;
     x_q[0] = 1;
     y_q    = f.Forward(q, x_q);
     check  = 1.;
     ok &= NearEqual(y_q[0] , check,  eps, eps);

     // check second order forward mode
     q      = 2;
     x_q[0] = 0;
     y_q    = f.Forward(q, x_q);
     check  = 0.;
     ok &= NearEqual(y_q[0] , check,  eps, eps);

     // --------------------------------------------------------------------
     // Check reverse mode results
     //
     // third order reverse mode
     q     = 3;
     vector<double> w(m), dw(n * q);
     w[0]  = 1.;
     dw    = f.Reverse(q, w);
     check = 1.;
     ok &= NearEqual(dw[0] , check,  eps, eps);
     check = 0.;
     ok &= NearEqual(dw[1] , check,  eps, eps);
     ok &= NearEqual(dw[2] , check,  eps, eps);

     // --------------------------------------------------------------------
     // forward mode sparstiy pattern
     size_t p = n;
     CppAD::vectorBool r1(n * p), s1(m * p);
     r1[0] = true;          // compute sparsity pattern for x[0]
     s1    = f.ForSparseJac(p, r1);
     ok  &= s1[0] == true;  // f[0] depends on x[0]

     // --------------------------------------------------------------------
     // reverse mode sparstiy pattern
     q = m;
     CppAD::vectorBool s2(q * m), r2(q * n);
     s2[0] = true;          // compute sparsity pattern for f[0]
     r2    = f.RevSparseJac(q, s2);
     ok  &= r2[0] == true;  // f[0] depends on x[0]

     // --------------------------------------------------------------------
     // Hessian sparsity (using previous ForSparseJac call)
     CppAD::vectorBool s3(m), h(p * n);
     s3[0] = true;        // compute sparsity pattern for f[0]
     h     = f.RevSparseJac(p, s3);
     ok  &= h[0] == true; // second partial of f[0] w.r.t. x[0] may be non-zero

     // -----------------------------------------------------------------
     // Free all memory associated with the object r_ptr
     destroy_r();

     // -----------------------------------------------------------------
     // Free all temporary work space associated with old_atomic objects.
     // (If there are future calls to user atomic functions, they will
     // create new temporary work space.)
     CppAD::user_atomic<double>::clear();

     return ok;
}

Input File: example/deprecated/old_usead_1.cpp