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Fixed bug #702 and added unit test.

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Thanks to Alexander Werner for the report.
This commit is contained in:
Christoph Hertzberg 2013-11-07 18:32:24 +01:00
parent 76c230a84d
commit ae83f5ede9
3 changed files with 48 additions and 5 deletions
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8
unsupported/Eigen/src/AutoDiff/AutoDiffScalar.h
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@ -599,12 +599,10 @@ atan2(const AutoDiffScalar<DerTypeA>& a, const AutoDiffScalar<DerTypeB>& b)
PlainADS ret;
ret.value() = atan2(a.value(), b.value());
Scalar tmp2 = a.value() * a.value();
Scalar tmp3 = b.value() * b.value();
Scalar tmp4 = tmp3/(tmp2+tmp3);
Scalar squared_hypot = a.value() * a.value() + b.value() * b.value();
if (tmp4!=0)
ret.derivatives() = (a.derivatives() * b.value() - a.value() * b.derivatives()) * (tmp2+tmp3);
// if (squared_hypot==0) the derivation is undefined and the following results in a NaN:
ret.derivatives() = (a.derivatives() * b.value() - a.value() * b.derivatives()) / squared_hypot;
return ret;
}

1
unsupported/test/CMakeLists.txt
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@ -28,6 +28,7 @@ endif(ADOLC_FOUND)
ei_add_test(NonLinearOptimization)
ei_add_test(NumericalDiff)
ei_add_test(autodiff_scalar)
ei_add_test(autodiff)
if (NOT CMAKE_CXX_COMPILER MATCHES "clang\\+\\+$")

44
unsupported/test/autodiff_scalar.cpp Normal file
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@ -0,0 +1,44 @@
// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2013 Christoph Hertzberg <chtz@informatik.uni-bremen.de>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
#include "main.h"
#include <unsupported/Eigen/AutoDiff>
/*
* In this file scalar derivations are tested for correctness.
* TODO add more tests!
*/
template<typename Scalar> void check_atan2()
{
typedef Matrix<Scalar, 1, 1> Deriv1;
typedef AutoDiffScalar<Deriv1> AD;
AD x(internal::random<Scalar>(-3.0, 3.0), Deriv1::UnitX());
using std::exp;
Scalar r = exp(internal::random<Scalar>(-10, 10));
AD s = sin(x), c = cos(x);
AD res = atan2(r*s, r*c);
VERIFY_IS_APPROX(res.value(), x.value());
VERIFY_IS_APPROX(res.derivatives(), x.derivatives());
}
void test_autodiff_scalar()
{
for(int i = 0; i < g_repeat; i++) {
CALL_SUBTEST_1( check_atan2<float>() );
CALL_SUBTEST_2( check_atan2<double>() );
}
}