134 lines
4.4 KiB
C++
134 lines
4.4 KiB
C++
/*
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Copyright 2016 Statoil ASA.
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This file is part of the Open Porous Media project (OPM).
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OPM is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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OPM is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with OPM. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef COMMON_UTIL_NUMERIC_CMP
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#define COMMON_UTIL_NUMERIC_CMP
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#include <cstddef>
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#include <vector>
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#include <type_traits>
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#include <cmath>
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#include <algorithm>
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namespace Opm {
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/// In the namespace cmp are implemented functions for
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/// approximate comparison of double values based on absolute
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/// and relative difference. There are three functions:
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///
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/// scalar_equal<T>() : Compare two <T> values.
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///
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/// ptr_equal<T>(): This compares all the element in the
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/// two T * pointers.
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///
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/// vector_equal<T>(): This compares all the elements in
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/// two std::vector<T> instances.
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///
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/// For both vector_equal<T>() and ptr_equal<T>() the
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/// actual comparison is based on the scalar_equal<T>()
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/// function. All functions exist as two overloads, one which
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/// takes explicit input values for the absolute and relative
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/// epsilon, and one which uses default values.
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///
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/// The comparison functions are implemented as templates, with
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/// the following caveats:
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///
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/// 1. The static_assert() in scalar_equal<T> ensures that only
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/// floating point types can be used.
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///
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/// 2. The default epsilon values are of type double -
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/// irrespective of the type of data being compared.
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///
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/// For more details of floating point comparison please consult
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/// this reference:
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///
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/// https://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/
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namespace cmp {
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const double default_abs_epsilon = 1e-8;
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const double default_rel_epsilon = 1e-5;
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template<typename T>
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bool scalar_equal(T value1, T value2, T abs_eps , T rel_eps) {
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static_assert(std::is_floating_point<T>::value, "Function scalar_equal() A can only be instantiated with floating point types");
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bool equal = true;
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T diff = std::fabs(value1 - value2);
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if (diff > abs_eps) {
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T scale = std::max(std::fabs(value1), std::fabs(value2));
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if (diff > scale * rel_eps) {
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equal = false;
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}
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}
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return equal;
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}
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template<typename T>
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bool scalar_equal(T value1, T value2) {
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return scalar_equal<T>( value1 , value2 , default_abs_epsilon , default_rel_epsilon );
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}
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template<typename T>
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bool vector_equal(const std::vector<T>& v1, const std::vector<T>& v2, T abs_eps, T rel_eps) {
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if (v1.size() != v2.size()) {
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return false;
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}
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for (size_t i = 0; i < v1.size(); i++) {
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if (!scalar_equal<T>( v1[i], v2[i], abs_eps, rel_eps ))
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return false;
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}
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return true;
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}
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template<typename T>
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bool vector_equal(const std::vector<T>& v1, const std::vector<T>& v2) {
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return vector_equal<T>(v1, v2, default_abs_epsilon, default_rel_epsilon);
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}
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template<typename T>
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bool array_equal(const T* p1, const T* p2, size_t num_elements, T abs_eps, T rel_eps) {
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if (memcmp(p1 , p2 , num_elements * sizeof * p1) == 0)
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return true;
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else {
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size_t index;
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for (index = 0; index < num_elements; index++) {
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if (!scalar_equal<T>( p1[index] , p2[index] , abs_eps , rel_eps)) {
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return false;
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}
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}
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}
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return true;
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}
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template<typename T>
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bool array_equal(const T* p1, const T* p2, size_t num_elements) {
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return array_equal<T>(p1, p2, num_elements , default_abs_epsilon, default_rel_epsilon);
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}
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}
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}
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#endif
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