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// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-or-later
// SPDX-FileCopyrightText: Bradley M. Bell <bradbell@seanet.com>
// SPDX-FileContributor: 2003-22 Bradley M. Bell
// ----------------------------------------------------------------------------
/*
{xrst_begin exp.cpp}
The AD exp Function: Example and Test
#####################################
{xrst_literal
// BEGIN C++
// END C++
}
{xrst_end exp.cpp}
*/
// BEGIN C++
# include <cppad/cppad.hpp>
# include <cmath>
bool exp(void)
{ bool ok = true;
using CppAD::AD;
using CppAD::NearEqual;
double eps = 10. * std::numeric_limits<double>::epsilon();
// domain space vector
size_t n = 1;
double x0 = 0.5;
CPPAD_TESTVECTOR(AD<double>) ax(n);
ax[0] = x0;
// declare independent variables and start tape recording
CppAD::Independent(ax);
// range space vector
size_t m = 1;
CPPAD_TESTVECTOR(AD<double>) ay(m);
ay[0] = CppAD::exp(ax[0]);
// create f: x -> y and stop tape recording
CppAD::ADFun<double> f(ax, ay);
// check value
double check = std::exp(x0);
ok &= NearEqual(ay[0], check, eps, eps);
// forward computation of first partial w.r.t. x[0]
CPPAD_TESTVECTOR(double) dx(n);
CPPAD_TESTVECTOR(double) dy(m);
dx[0] = 1.;
dy = f.Forward(1, dx);
ok &= NearEqual(dy[0], check, eps, eps);
// reverse computation of derivative of y[0]
CPPAD_TESTVECTOR(double) w(m);
CPPAD_TESTVECTOR(double) dw(n);
w[0] = 1.;
dw = f.Reverse(1, w);
ok &= NearEqual(dw[0], check, eps, eps);
// use a VecAD<Base>::reference object with exp
CppAD::VecAD<double> v(1);
AD<double> zero(0);
v[zero] = x0;
AD<double> result = CppAD::exp(v[zero]);
ok &= NearEqual(result, check, eps, eps);
return ok;
}
// END C++
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