Prev Next json_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 .
Json Comparison Operators: Example and Test

Source Code 

# include <cppad/cppad.hpp>

bool comp_op(void)
{   bool ok = true;
    using CppAD::vector;
    using CppAD::AD;
    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] )
    // use single quote to avoid having to escape double quote
    std::string json =
        "{\n"
        "   'function_name'  : 'comp_op example',\n"
        "   'op_define_vec'  : [ 3, [\n"
        "       { 'op_code':1, 'name':'comp_lt'            } ,\n"
        "       { 'op_code':2, 'name':'sub',     'n_arg':2 } ,\n"
        "       { 'op_code':3, 'name':'log',     'n_arg':1 } ]\n"
        "   ],\n"
        "   'n_dynamic_ind'  : 1,\n"
        "   'n_variable_ind' : 1,\n"
        "   'constant_vec'   : [ 0, [ ] ],\n"
        "   'op_usage_vec'   : [ 3, [\n"
        "       [ 1, 0, 2, [2, 1 ] ] ,\n" // x[0] < p[0]
        "       [ 2, 1, 2          ] ,\n" // p[0] - x[0]
        "       [ 3, 3             ] ]\n" // log( p[0] - x[0] )
        "   ],\n"
        "   'dependent_vec' : [ 1, [4] ] \n"
        "}\n";
    // Convert the single quote to double quote
    for(size_t i = 0; i < json.size(); ++i)
        if( json[i] == '\'' ) json[i] = '"';
    //
    // f(x, p) = log( p[0] - x[0] )
    CppAD::ADFun<double> f;
    f.from_json(json);
    ok &= f.Domain() == 1;
    ok &= f.Range() == 1;
    ok &= f.size_dyn_ind() == 1;
    //
    // set independent variables and parameters
    vector<double> p(1), x(1);
    p[0] = 0.3;
    x[0] = 0.2;
    //
    // compute y = f(x, p)
    f.new_dynamic(p);
    vector<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 Json graph and back again
    json = f.to_json();
    // std::cout << json;
    f.from_json(json);
    // -----------------------------------------------------------------------
    //
    // 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/json/comp_op.cpp