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jit_compare_change.cpp

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The JIT compare_change Argument: Example and Test

Source

# include <cstddef>
# include <iostream>
# include <fstream>
# include <map>

// DLL_EXT
# ifdef _WIN32
# define DLL_EXT ".dll"
# else
# define DLL_EXT ".so"
# endif

# include <cppad/cppad.hpp>
bool compare_change(void)
{   bool ok = true;
    //
    using CppAD::AD;
    using CppAD::ADFun;
    using CppAD::Independent;
    using CppAD::NearEqual;
    //
    // nx, ny
    size_t nx = 2, ny = 1;
    //
    // f(x) = x_0 + x_1
    CPPAD_TESTVECTOR( AD<double> ) ax(nx), ay(ny);
    ax[0] = 0.0;
    ax[1] = 1.0;
    Independent(ax);
    if( ax[0] < ax[1] )
        ay[0] = ax[1] - ax[0];
    else
        ay[0] = ax[0] - ax[1];
    ADFun<double> f(ax, ay);
    f.function_name_set("f");
    //
    // csrc_file
    // created in std::filesystem::current_path
    std::string c_type    = "double";
    std::string csrc_file = "compare_change.c";
    std::ofstream ofs;
    ofs.open(csrc_file , std::ofstream::out);
    f.to_csrc(ofs, c_type);
    ofs.close();
    //
    // dll_file
    // created in std::filesystem::current_path
    std::string dll_file = "jit_to_csrc" DLL_EXT;
    CPPAD_TESTVECTOR( std::string) csrc_files(1);
    csrc_files[0] = csrc_file;
    std::map< std::string, std::string > options;
    std::string err_msg = CppAD::create_dll_lib(dll_file, csrc_files, options);
    if( err_msg != "" )
    {   std::cerr << "jit_to_csrc: err_msg = " << err_msg << "\n";
        return false;
    }
    // dll_linker
    CppAD::link_dll_lib dll_linker(dll_file, err_msg);
    if( err_msg != "" )
    {   std::cerr << "jit_to_csrc: err_msg = " << err_msg << "\n";
        return false;
    }
    //
    // void_ptr
    std::string function_name = "cppad_jit_f";
    void* void_ptr = dll_linker(function_name, err_msg);
    if( err_msg != "" )
    {   std::cerr << "jit_to_csrc: err_msg = " << err_msg << "\n";
        return false;
    }
    //
    // jit_double
    using CppAD::jit_double;
    //
    // f_ptr
    jit_double f_ptr =
        reinterpret_cast<jit_double>(void_ptr);
    //
    // x, y, compare_change
    // y = f(x)
    size_t compare_change = 0;
    std::vector<double> x(nx), y(ny);
    x[0] = 0.1;
    x[1] = 0.2;
    f_ptr(nx, x.data(), ny, y.data(), &compare_change);
    //
    // ok
    // comparison same as when recorded (compare_change the same)
    ok &= compare_change == 0;
    //
    // ok
    double eps99 = 99.0 * std::numeric_limits<double>::epsilon();
    double check = x[1] - x[0];
    ok &= NearEqual(y[0], check, eps99, eps99);
    //
    // x, y, compare_change
    x[0] = 0.5;
    x[1] = 0.1;
    f_ptr(nx, x.data(), ny, y.data(), &compare_change);
    //
    // ok
    // comparison different from when recorded (compare_change increased)
    ok &= compare_change == 1;
    //
    // ok
    check = x[1] - x[0];
    ok &= NearEqual(y[0], check, eps99, eps99);
    //
    // x, y, compare_change
    x[0] = 1.0;
    x[1] = 5.0;
    f_ptr(nx, x.data(), ny, y.data(), &compare_change);
    //
    // ok
    // comparison as as when recorded (compare_change the same)
    ok &= compare_change == 1;
    //
    // ok
    check = x[1] - x[0];
    ok &= NearEqual(y[0], check, eps99, eps99);
    //
    return ok;
}