\(\newcommand{\W}[1]{ \; #1 \; }\) \(\newcommand{\R}[1]{ {\rm #1} }\) \(\newcommand{\B}[1]{ {\bf #1} }\) \(\newcommand{\D}[2]{ \frac{\partial #1}{\partial #2} }\) \(\newcommand{\DD}[3]{ \frac{\partial^2 #1}{\partial #2 \partial #3} }\) \(\newcommand{\Dpow}[2]{ \frac{\partial^{#1}}{\partial {#2}^{#1}} }\) \(\newcommand{\dpow}[2]{ \frac{ {\rm d}^{#1}}{{\rm d}\, {#2}^{#1}} }\)

graph_atom_op.cpp

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C++ AD Graph Atomic Three Functions: Example and Test

Source Code

# include <cppad/cppad.hpp>

bool atom_op(void)
{  bool ok = true;
   using std::string;
   // -----------------------------------------------------------------------
   // Define f_0 (x_0, x_1; p) = x_1 + p_0 * x_0
   //
   // This function does not have an atomic function operator
   // node_1 : p[0]
   // node_2 : x[0]
   // node_3 : x[1]
   // node_4 : p[0] * x[0]
   // node_5 : x[1] + p[0] * x[0]
   // y[0]   = x[1] + p[0] * x[0]
   //
   // C++ graph object
   CppAD::cpp_graph graph_obj;
   //
   // operator being used
   CppAD::graph::graph_op_enum op_enum;
   //
   // set scalars
   graph_obj.function_name_set("f(x; p)");
   size_t n_dynamic_ind = 1;
   graph_obj.n_dynamic_ind_set(n_dynamic_ind);
   size_t n_variable_ind = 2;
   graph_obj.n_variable_ind_set(n_variable_ind);
   //
   // node_4 : p[0] * x[0]
   op_enum = CppAD::graph::mul_graph_op;
   graph_obj.operator_vec_push_back(op_enum);
   graph_obj.operator_arg_push_back(1);
   graph_obj.operator_arg_push_back(2);
   //
   // node_5 : x[1] + p[0] * x[0]
   op_enum = CppAD::graph::add_graph_op;
   graph_obj.operator_vec_push_back(op_enum);
   graph_obj.operator_arg_push_back(3);
   graph_obj.operator_arg_push_back(4);
   //
   // y[0]   = x[1] + p[0] * x[0]
   graph_obj.dependent_vec_push_back(5);
   //
   // f(x, p) = x_1 + p_0 * x_0
   CppAD::ADFun<float> f;
   f.from_graph(graph_obj);
   //
   ok &= f.Domain() == 2;
   ok &= f.Range() == 1;
   ok &= f.size_dyn_ind() == 1;
   //
   // A ckhpoint_two function with name f(x; p) is derived from
   // an atomic_three function with the same name.
   bool internal_bool    = false;
   bool use_hes_sparsity = false;
   bool use_base2ad      = false;
   bool use_in_parallel  = false;
   CppAD::chkpoint_two<float> chk_f(f, "f(x; p)",
      internal_bool, use_hes_sparsity, use_base2ad, use_in_parallel
   );
   // -----------------------------------------------------------------------
   // g (u_0, u_1; p, q) = f(u_0 + q_0, u_1 + q_1, p)
   //                    = u_1 + q_1 + p_0 * ( u_0 + q_0 )
   //
   // This function has an atomic function operator with name f(x; p)
   // node_1 : q[0]
   // node_2 : q[1]
   // node_3 : u[0]
   // node_4 : u[1]
   // node_5 : u[0] + q[0]
   // node_6 : u[1] + q[1]
   // node_7 : f( u[0] + q[0], u[1] + q[1]; p)
   // y[0]   = u[1] + q[1] + p[0] * (u[0]  + q[0])
   //
   graph_obj.initialize();
   //
   graph_obj.function_name_set("g(u; p, q)");
   n_dynamic_ind = 2;
   graph_obj.n_dynamic_ind_set(n_dynamic_ind);
   n_variable_ind = 2;
   graph_obj.n_variable_ind_set(n_variable_ind);
   //
   // node_5 : u[0] + q[0]
   op_enum = CppAD::graph::add_graph_op;
   graph_obj.operator_vec_push_back(op_enum);
   graph_obj.operator_arg_push_back(3);
   graph_obj.operator_arg_push_back(1);
   //
   // node_6 : u[1] + q[1]
   graph_obj.operator_vec_push_back(op_enum);
   graph_obj.operator_arg_push_back(4);
   graph_obj.operator_arg_push_back(2);
   //
   // node_7 : f( u[0] + q[0], u[1] + q[1]; p)
   //
   // name_index, n_result, n_arg come before first_node
   size_t name_index = graph_obj.atomic_name_vec_size();
   graph_obj.atomic_name_vec_push_back("f(x; p)");
   //
   op_enum = CppAD::graph::atom_graph_op;
   graph_obj.operator_vec_push_back(op_enum);
   graph_obj.operator_arg_push_back(name_index);  // name_index
   graph_obj.operator_arg_push_back(1);           // n_result
   graph_obj.operator_arg_push_back(2);           // n_node_arg
   graph_obj.operator_arg_push_back(5);           // first node arg
   graph_obj.operator_arg_push_back(6);           // second node arg
   //
   // y[0]   = u[1] + q[1] + p[0] * (u[0]  + q[0])
   graph_obj.dependent_vec_push_back(7);
   // ------------------------------------------------------------------------
   CppAD::ADFun<float> g;
   g.from_graph(graph_obj);
   // ------------------------------------------------------------------------
   ok &= g.Domain() == 2;
   ok &= g.Range() == 1;
   ok &= g.size_dyn_ind() == 2;
   //
   // set p in g(u; p, q)
   CPPAD_TESTVECTOR(float) p(1);
   p[0] = 2.0;
   chk_f.new_dynamic(p);
   //
   // set q in g(u; p, q)
   CPPAD_TESTVECTOR(float) q(2);
   q[0] = 3.0;
   q[1] = 4.0;
   g.new_dynamic(q);
   //
   // evalute g(u; p, q)
   CPPAD_TESTVECTOR(float) u(2), y(1);
   u[0] = 5.0;
   u[1] = 6.0;
   y    = g.Forward(0, u);
   //
   // check value
   ok &= y[0] == u[1] + q[1] + p[0] * (u[0]  + q[0]);
   // ------------------------------------------------------------------------
   g.to_graph(graph_obj);
   g.from_graph(graph_obj);
   // ------------------------------------------------------------------------
   ok &= g.Domain() == 2;
   ok &= g.Range() == 1;
   ok &= g.size_dyn_ind() == 2;
   //
   // set p in g(u; p, q)
   p[0] = 3.0;
   chk_f.new_dynamic(p);
   //
   // set q in g(u; p, q)
   q[0] = 4.0;
   q[1] = 5.0;
   g.new_dynamic(q);
   //
   // evalute g(u; p, q)
   u[0] = 6.0;
   u[1] = 7.0;
   y    = g.Forward(0, u);
   //
   // check value
   ok &= y[0] == u[1] + q[1] + p[0] * (u[0]  + q[0]);
   // ------------------------------------------------------------------------
   return ok;
}