Json add Operator: Example and Test

json_discrete_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 add Operator: Example and Test
Source Code


# include <cppad/cppad.hpp>

namespace {
    double heaviside(const double &x)
    {   if( x < 0.0 )
            return 0.0;
        if( x == 0.0 )
            return 0.5;
        return 1.0;
    }
    CPPAD_DISCRETE_FUNCTION(double, heaviside)
}

bool discrete_op(void)
{   bool ok = true;
    using CppAD::vector;
    using CppAD::AD;
    //
    // The discrete function does not exist until its AD version is called
    heaviside( CppAD::AD<double>( 0.0 ) );
    //
    //
    // AD graph example
    // node_1 : p[0]
    // node_2 : x[0]
    // node_3 : heaviside(p[0])
    // node_4 : heaviside(p[1])
    // node_5 = heaviside(p[0]) + heaviside(p[1])
    // y[0]   = heaviside(p[0]) + heaviside(p[1])
    // use single quote to avoid having to escape double quote
    std::string json =
        "{\n"
        "   'function_name'  : 'discrete_op example',\n"
        "   'op_define_vec'  : [ 2, [\n"
        "       { 'op_code':1, 'name':'add',      'n_arg':2 } ,\n"
        "       { 'op_code':2, 'name':'discrete' }            ]\n"
        "   ],\n"
        "   'n_dynamic_ind'  : 1,\n"
        "   'n_variable_ind' : 1,\n"
        "   'constant_vec'   : [ 0, [ ] ],\n"
        "   'op_usage_vec'   : [ 3, [\n"
        "       [ 2, 'heaviside', 1, 1, [ 1 ] ] ,\n" // heaviside(p[0])
        "       [ 2, 'heaviside', 1, 1, [ 2 ] ] ,\n" // heaviside(x[0])
        "       [ 1, 3, 4 ] ]\n"  // heaviside(p[0]) + heaviside(x[0])
        "   ],\n"
        "   'dependent_vec' : [ 1, [5] ] \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) = x_0 + ( p_0 + p_1 )
    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
    CPPAD_TESTVECTOR(double) p(1), x(1);
    p[0] = 0.0;
    x[0] = 2.0;
    //
    // compute y = f(x, p)
    f.new_dynamic(p);
    CPPAD_TESTVECTOR(double) y = f.Forward(0, x);
    //
    // check result
    ok &= y[0] == heaviside(p[0]) + heaviside(x[0]);
    // -----------------------------------------------------------------------
    // Convert to Json graph and back again
    json = f.to_json();
    // std::cout << "json = " << json;
    f.from_json(json);
    // -----------------------------------------------------------------------
    ok &= f.Domain() == 1;
    ok &= f.Range() == 1;
    ok &= f.size_dyn_ind() == 1;
    //
    // set independent variables and parameters
    p[0] = -2.0;
    x[0] = 2.0;
    //
    // compute y = f(x, p)
    f.new_dynamic(p);
    y = f.Forward(0, x);
    //
    // check result
    ok &= y[0] == heaviside(p[0]) + heaviside(x[0]);
    //
    return ok;
}

Input File: example/json/discrete_op.cpp