Convert a Variable or Dynamic Parameter a Constant: Example and Test

var2par.cpp

Headings

@(@\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 . Convert a Variable or Dynamic Parameter a Constant: Example and Test


# include <cppad/cppad.hpp>


bool Var2Par(void)
{   bool ok = true;
    using CppAD::AD;
    using CppAD::Value;
    using CppAD::Var2Par;

    // independent variables
    size_t nx = 2;
    CPPAD_TESTVECTOR(AD<double>) ax(nx);
    ax[0] = 3.;
    ax[1] = 4.;

    // independent dynamic paramers
    size_t np = 1;
    CPPAD_TESTVECTOR(AD<double>) ap(np);
    ap[0] = 5.;

    // declare independent variables and dynamic parameters
    CppAD::Independent(ax, ap);

    // range space vector
    size_t ny = 2;
    CPPAD_TESTVECTOR(AD<double>) ay(ny);
    ay[0] = - ax[1] * Var2Par(ax[0]);    // same as ay[0] = -ax[1] * 3.;
    ay[1] = - ax[1] * Var2Par(ap[0]);    // same as ay[1] = -ax[1] * 5.;

    // Must convert these objects to constants before calling Value
    ok &= ( Value( Var2Par(ax[0]) ) == 3. );
    ok &= ( Value( Var2Par(ax[1]) ) == 4. );
    ok &= ( Value( Var2Par(ap[0]) ) == 5. );
    ok &= ( Value( Var2Par(ay[0]) ) == -12. );
    ok &= ( Value( Var2Par(ay[1]) ) == -20. );

    // create f: x -> y and stop tape recording
    CppAD::ADFun<double> f(ax, ay);

    // All AD object are currently constants
    ok &= (Value(ax[0]) ==  3.);
    ok &= (Value(ax[1]) ==  4.);
    ok &= (Value(ap[0]) ==  5.);
    ok &= (Value(ay[0]) == -12.);
    ok &= (Value(ay[1]) == -20.);

    // evaluate zero order forward mode
    // (note that the only real variable in this recording is x[1])
    CPPAD_TESTVECTOR(double) x(nx), p(np), y(ny);
    x[0] = 6.;
    x[1] = 7.;
    p[0] = 8.;
    f.new_dynamic(p);
    y    = f.Forward(0, x);
    ok  &= y[0] == - x[1] * 3.0;
    ok  &= y[1] == - x[1] * 5.0;

    return ok;
}

Input File: example/general/var2par.cpp