C++ AD Graph Comparison Operators: Example and Test

graph_comp_op.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}} }@)@This is cppad-20221105 documentation. Here is a link to its current documentation . C++ AD Graph Comparison Operators: Example and Test
Source Code


# include <cppad/cppad.hpp>

bool comp_op(void)
{   bool ok = true;
    using std::string;
    double eps99 = 99.0 * std::numeric_limits<double>::epsilon();
    //
    // AD graph example
    // node_1 : p[0]
    // node_2 : x[0]
    //        : x[0] < p[0]
    // node_3 : p[0] - x[0]
    // node_4 : log( p[0] - x[0] )
    // y[0]   = log( 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("comp_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);
    //
    // x[0] < p[0]
    op_enum = CppAD::graph::comp_lt_graph_op;
    graph_obj.operator_vec_push_back(op_enum);
    graph_obj.operator_arg_push_back(2);
    graph_obj.operator_arg_push_back(1);
    //
    // node_3 : p[0] - x[0]
    op_enum = CppAD::graph::sub_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_4 : log( p[0] - x[0] )
    op_enum = CppAD::graph::log_graph_op;
    graph_obj.operator_vec_push_back(op_enum);
    graph_obj.operator_arg_push_back(3);
    //
    // y[0]   = log( p[0] - x[0] )
    graph_obj.dependent_vec_push_back(4);
    //
    // f(x, p) = log( p[0] - x[0] )
    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] = 0.3;
    x[0] = 0.2;
    //
    // compute y = f(x, p)
    f.new_dynamic(p);
    CPPAD_TESTVECTOR(double) y = f.Forward(0, x);
    //
    //  x[0] < p[0] so comparison should not have changed
    ok &= f.compare_change_number() == 0;
    //
    // check result
    double check = std::log( p[0] - x[0] );
    ok &= CppAD::NearEqual(y[0], check, eps99, eps99);
    //
    // case where comparison is false
    f.check_for_nan(false); // suppress checking for nan for this test
    x[0] = 0.4;
    y = f.Forward(0, x);
    ok &= f.compare_change_number() == 1;
    //
    // -----------------------------------------------------------------------
    // Convert to Graph graph and back again
    f.to_graph(graph_obj);
    // std::cout << graph;
    f.from_graph(graph_obj);
    // -----------------------------------------------------------------------
    //
    // compute y = f(x, p)
    f.new_dynamic(p);
    x[0] = 0.2;
    y = f.Forward(0, x);
    //
    // check result
    ok &= CppAD::NearEqual(y[0], check, eps99, eps99);
    //
    // case where comparison is false
    x[0] = 0.4;
    y = f.Forward(0, x);
    ok &= f.compare_change_number() == 1;
    //
    return ok;
}

Input File: example/graph/comp_op.cpp