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

graph_print_op.cpp

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C++ AD Graph print Operator: Example and Test

Source Code

# include <cppad/cppad.hpp>

bool print_op(void)
{  bool ok = true;
   using std::string;
   std::stringstream stream_out;
   double eps99 = 99.0 * std::numeric_limits<double>::epsilon();
   //
   // AD graph example
   // node_1 : p[0]
   // node_2 : x[0]
   //        : print(p[0], "p[0] = ", p[0], "\n")
   //        : print(x[0], "x[0] = ", x[0], "\n")
   // node_3 : log(p[0])
   // node_4 : log(x[0])
   // node_5 = log(p[0]) + log(x[0])
   // y[0]   = log(p[0]) + log(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("print_op example");
   size_t n_dynamic_ind = 1;
   graph_obj.n_dynamic_ind_set(n_dynamic_ind);
   size_t n_variable_ind = 1;
   graph_obj.n_variable_ind_set(n_variable_ind);
   //
   // if p[0] <= 0: print "p[0] = ", p[0], "\n"
   op_enum  = CppAD::graph::print_graph_op;
   graph_obj.operator_vec_push_back(op_enum);
   size_t before = graph_obj.print_text_vec_size();
   graph_obj.print_text_vec_push_back("p[0] = ");
   graph_obj.operator_arg_push_back(before);
   size_t after = graph_obj.print_text_vec_size();
   graph_obj.print_text_vec_push_back("\n");
   graph_obj.operator_arg_push_back(after);
   graph_obj.operator_arg_push_back(1);
   graph_obj.operator_arg_push_back(1);
   //
   // if x[0] <= 0: print "x[0] = ", x[0], "\n"
   graph_obj.operator_vec_push_back(op_enum);
   before = graph_obj.print_text_vec_size();
   graph_obj.print_text_vec_push_back("x[0] = ");
   graph_obj.operator_arg_push_back(before);
   graph_obj.operator_arg_push_back(after);
   graph_obj.operator_arg_push_back(2);
   graph_obj.operator_arg_push_back(2);
   //
   // node_3 : log(p[0])
   op_enum = CppAD::graph::log_graph_op;
   graph_obj.operator_vec_push_back(op_enum);
   graph_obj.operator_arg_push_back(1);
   //
   // node_4 : log(x[0])
   graph_obj.operator_vec_push_back(op_enum);
   graph_obj.operator_arg_push_back(2);
   //
   // node_5: log(p[0]) + log(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] = log(p[0]) + log(x[0])
   graph_obj.dependent_vec_push_back(5);
   //
   // f(x, p) = log(x) + log(p)
   CppAD::ADFun<double> f;
   f.from_graph(graph_obj);
   ok &= f.Domain() == 1;
   ok &= f.Range() == 1;
   ok &= f.size_dyn_ind() == 1;
   //
   // set independent variables and parameters
   CPPAD_TESTVECTOR(double) p(1), x(1);
   p[0] = 1.0;
   x[0] = 2.0;
   //
   // compute y = f(x, p)
   f.new_dynamic(p);
   CPPAD_TESTVECTOR(double) y = f.Forward(0, x, stream_out);
   //
   // check result
   ok &= stream_out.str() == "";
   double check = std::log(p[0]) + std::log(x[0]);
   ok &= CppAD::NearEqual(y[0], check, eps99, eps99);
   //
   // -----------------------------------------------------------------------
   // Convert function to graph and back again
   f.to_graph(graph_obj);
   f.from_graph(graph_obj);
   // -----------------------------------------------------------------------
   ok &= f.Domain() == 1;
   ok &= f.Range() == 1;
   ok &= f.size_dyn_ind() == 1;
   //
   // set independent variables and parameters
   p[0] = 1.0;
   x[0] = -2.0;
   //
   // compute y = f(x, p)
   f.new_dynamic(p);
   f.check_for_nan(false);
   y = f.Forward(0, x, stream_out);
   //
   // check result
   ok &= stream_out.str() == "x[0] = -2\n";
   ok &= std::isnan(y[0]);
   //
   return ok;
}