/* --------------------------------------------------------------------------
CppAD: C++ Algorithmic Differentiation: Copyright (C) 2003-17 Bradley M. Bell

CppAD is distributed under the terms of the
             Eclipse Public License Version 2.0.

This Source Code may also be made available under the following
Secondary License when the conditions for such availability set forth
in the Eclipse Public License, Version 2.0 are satisfied:
      GNU General Public License, Version 2.0 or later.
---------------------------------------------------------------------------- */

/*
Old example now just used for validation testing.
*/
# include <cppad/cppad.hpp>

bool Cosh(void)
{   bool ok = true;
    using CppAD::sinh;
    using CppAD::cosh;
    using namespace CppAD;
    double eps99 = 99.0 * std::numeric_limits<double>::epsilon();

    // independent variable vector
    CPPAD_TESTVECTOR(AD<double>) U(1);
    U[0]     = 1.;
    Independent(U);

    // dependent variable vector
    CPPAD_TESTVECTOR(AD<double>) Z(1);
    Z[0] = cosh(U[0]);

    // create f: U -> Z and vectors used for derivative calculations
    ADFun<double> f(U, Z);
    CPPAD_TESTVECTOR(double) v(1);
    CPPAD_TESTVECTOR(double) w(1);

    // check value
    double sinh_u = sinh( Value(U[0]) );
    double cosh_u = cosh( Value(U[0]) );

    ok &= NearEqual(cosh_u, Value(Z[0]),  eps99 , eps99);

    // forward computation of partials w.r.t. u
    size_t j;
    size_t p     = 5;
    double jfac  = 1.;
    v[0]         = 1.;
    for(j = 1; j < p; j++)
    {   w     = f.Forward(j, v);

        double value;
        if( j % 2 == 1 )
            value = sinh_u;
        else
            value = cosh_u;

        jfac *= double(j);
        ok &= NearEqual(w[0], value/jfac, eps99, eps99); // d^jz/du^j
        v[0]  = 0.;
    }

    // reverse computation of partials of Taylor coefficients
    CPPAD_TESTVECTOR(double) r(p);
    w[0]  = 1.;
    r     = f.Reverse(p, w);
    jfac  = 1.;
    for(j = 0; j < p; j++)
    {
        double value;
        if( j % 2 == 0 )
            value = sinh_u;
        else
            value = cosh_u;

        ok &= NearEqual(r[j], value/jfac, eps99, eps99); // d^jz/du^j

        jfac *= double(j + 1);
    }

    return ok;
}
