Added thirdparty: boost library

thirdparty/include/boost/math/ccmath/fabs.hpp

@@ -0,0 +1,41 @@
+//  (C) Copyright Matt Borland 2021.
+//  Use, modification and distribution are subject to the
+//  Boost Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+//  Constepxr implementation of fabs (see c.math.abs secion 26.8.2 of the ISO standard)
+
+#ifndef BOOST_MATH_CCMATH_FABS
+#define BOOST_MATH_CCMATH_FABS
+
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/fabs.hpp> can only be used in C++17 and later."
+#endif
+
+#include <boost/math/ccmath/abs.hpp>
+
+namespace boost::math::ccmath {
+
+template <typename T>
+inline constexpr auto fabs(T x) noexcept
+{
+    return boost::math::ccmath::abs(x);
+}
+
+inline constexpr float fabsf(float x) noexcept
+{
+    return boost::math::ccmath::abs(x);
+}
+
+#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
+inline constexpr long double fabsl(long double x) noexcept
+{
+    return boost::math::ccmath::abs(x);
+}
+#endif
+
+}
+
+#endif // BOOST_MATH_CCMATH_FABS