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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
// ----------------------------------------------------------------------------
/*
Test of directional derivative in AD< AD< double > > case.
*/
# include <cppad/cppad.hpp>
bool fabs(void)
{ // test if CppAD::abs uses if statement during forward computations
bool ok = true;
using CppAD::Independent;
using CppAD::ADFun;
typedef CppAD::AD<double> ADdouble;
typedef CppAD::AD< ADdouble > ADDdouble;
// af(x) = |x|
CPPAD_TESTVECTOR( ADDdouble ) aax(1), aay(1);
aax[0] = ADDdouble(0.);
CppAD::Independent(aax);
aay[0] = fabs(aax[0]);
CppAD::ADFun< ADdouble > af(aax, aay);
// f(x) = |x|
CPPAD_TESTVECTOR( ADdouble ) ax(1), ay(1);
ax[0] = ADdouble(0.);
CppAD::Independent(ax);
ay = af.Forward(0, ax);
CppAD::ADFun<double> f(ax, ay);
// compute derivative of af at a positive argument
CPPAD_TESTVECTOR( ADdouble ) adx(1), ady(1);
ax[0] = 1.;
ay = af.Forward(0, ax);
adx[0] = 1;
ady = af.Forward(1, adx);
ok &= (ady[0] == 1.);
// compute derivative of af at a zero argument
ax[0] = 0.;
ay = af.Forward(0, ax);
adx[0] = 1;
ady = af.Forward(1, adx);
ok &= (ady[0] == 0.);
// compute derivative of f at zero argument
CPPAD_TESTVECTOR(double) x(1), y(1), dx(1), dy(1);
x[0] = 0.;
y = f.Forward(0, x);
dx[0] = 1;
dy = f.Forward(1, dx);
ok &= (dy[0] == 0.);
// compute derivative of af at a negative argument
x[0] = -1.;
y = f.Forward(0, x);
dx[0] = 1;
dy = f.Forward(1, dx);
ok &= (dy[0] == -1.);
return ok;
}
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