comparison DEPENDENCIES/generic/include/boost/math/special_functions/atanh.hpp @ 16:2665513ce2d3

Add boost headers

+//    boost atanh.hpp header file
+
+//  (C) Copyright Hubert Holin 2001.
+//  (C) Copyright John Maddock 2008.
+//  Distributed under 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)
+
+// See http://www.boost.org for updates, documentation, and revision history.
+
+#ifndef BOOST_ATANH_HPP
+#define BOOST_ATANH_HPP
+
+#ifdef _MSC_VER
+#pragma once
+#endif
+
+
+#include <boost/config/no_tr1/cmath.hpp>
+#include <boost/config.hpp>
+#include <boost/math/tools/precision.hpp>
+#include <boost/math/policies/error_handling.hpp>
+#include <boost/math/special_functions/math_fwd.hpp>
+#include <boost/math/special_functions/log1p.hpp>
+
+// This is the inverse of the hyperbolic tangent function.
+
+namespace boost
+{
+    namespace math
+    {
+       namespace detail
+       {
+#if defined(__GNUC__) && (__GNUC__ < 3)
+        // gcc 2.x ignores function scope using declarations,
+        // put them in the scope of the enclosing namespace instead:
+        
+        using    ::std::abs;
+        using    ::std::sqrt;
+        using    ::std::log;
+        
+        using    ::std::numeric_limits;
+#endif
+        
+        // This is the main fare
+        
+        template<typename T, typename Policy>
+        inline T    atanh_imp(const T x, const Policy& pol)
+        {
+            BOOST_MATH_STD_USING
+            static const char* function = "boost::math::atanh<%1%>(%1%)";
+            
+            if(x < -1)
+            {
+               return policies::raise_domain_error<T>(
+                  function,
+                  "atanh requires x >= -1, but got x = %1%.", x, pol);
+            }
+            else if(x > 1)
+            {
+               return policies::raise_domain_error<T>(
+                  function,
+                  "atanh requires x <= 1, but got x = %1%.", x, pol);
+            }
+            else if(x < -1 + tools::epsilon<T>())
+            {
+               // -Infinity:
+               return -policies::raise_overflow_error<T>(function, 0, pol);
+            }
+            else if(x > 1 - tools::epsilon<T>())
+            {
+               // Infinity:
+               return policies::raise_overflow_error<T>(function, 0, pol);
+            }
+            else if(abs(x) >= tools::forth_root_epsilon<T>())
+            {
+                // http://functions.wolfram.com/ElementaryFunctions/ArcTanh/02/
+                if(abs(x) < 0.5f)
+                   return (boost::math::log1p(x, pol) - boost::math::log1p(-x, pol)) / 2;
+                return(log( (1 + x) / (1 - x) ) / 2);
+            }
+            else
+            {
+                // http://functions.wolfram.com/ElementaryFunctions/ArcTanh/06/01/03/01/
+                // approximation by taylor series in x at 0 up to order 2
+                T    result = x;
+                
+                if    (abs(x) >= tools::root_epsilon<T>())
+                {
+                    T    x3 = x*x*x;
+                    
+                    // approximation by taylor series in x at 0 up to order 4
+                    result += x3/static_cast<T>(3);
+                }
+                
+                return(result);
+            }
+        }
+       }
+
+        template<typename T, typename Policy>
+        inline typename tools::promote_args<T>::type atanh(T x, const Policy&)
+        {
+            typedef typename tools::promote_args<T>::type result_type;
+            typedef typename policies::evaluation<result_type, Policy>::type value_type;
+            typedef typename policies::normalise<
+               Policy, 
+               policies::promote_float<false>, 
+               policies::promote_double<false>, 
+               policies::discrete_quantile<>,
+               policies::assert_undefined<> >::type forwarding_policy;
+           return policies::checked_narrowing_cast<result_type, forwarding_policy>(
+              detail::atanh_imp(static_cast<value_type>(x), forwarding_policy()),
+              "boost::math::atanh<%1%>(%1%)");
+        }
+        template<typename T>
+        inline typename tools::promote_args<T>::type atanh(T x)
+        {
+           return boost::math::atanh(x, policies::policy<>());
+        }
+
+    }
+}
+
+#endif /* BOOST_ATANH_HPP */
+
+
+