From 84c10291f4dbf6b9f80842008c032e21de79c6c6 Mon Sep 17 00:00:00 2001
From: Jean-Paul Pelteret <jppelteret@gmail.com>
Date: Thu, 12 Apr 2018 14:39:01 +0200
Subject: [PATCH] Update ADNumberTraits

The addition of the scalar_type to the default definition for arithmetic
types increases the usefulness of this class for generic programming.
---
 .../deal.II/differentiation/ad/ad_number_traits.h  | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/include/deal.II/differentiation/ad/ad_number_traits.h b/include/deal.II/differentiation/ad/ad_number_traits.h
index 564523cae5..302923c741 100644
--- a/include/deal.II/differentiation/ad/ad_number_traits.h
+++ b/include/deal.II/differentiation/ad/ad_number_traits.h
@@ -641,7 +641,7 @@ namespace Differentiation
                typename std::enable_if<
                is_ad_number<F>::value &&
                std::is_arithmetic<T>::value
-               >::type * = 0)
+               >::type * = nullptr)
         {
           // We recursively call this function in case the AD number is a
           // nested one. The recursion ends when the extracted value is
@@ -661,7 +661,7 @@ namespace Differentiation
                typename std::enable_if<
                is_ad_number<F>::value &&
                is_ad_number<T>::value
-               >::type * = 0)
+               >::type * = nullptr)
         {
           return T(f);
         }
@@ -678,7 +678,7 @@ namespace Differentiation
         value (const F &f,
                typename std::enable_if<
                !is_ad_number<F>::value
-               >::type * = 0)
+               >::type * = nullptr)
         -> decltype (dealii::internal::NumberType< std::complex<T> >::value(f))
         {
           // We call the other function defined in the numbers
@@ -697,7 +697,7 @@ namespace Differentiation
                typename std::enable_if<
                is_ad_number<F>::value &&
                std::is_arithmetic<T>::value
-               >::type * = 0)
+               >::type * = nullptr)
         {
           // We recursively call this function in case the AD number is a
           // nested one. The recursion ends when the extracted value is
@@ -1021,6 +1021,12 @@ namespace Differentiation
       std::is_arithmetic<ScalarType>::value
       >::type>
     {
+      /**
+       * Underlying floating point value type.
+       * This could real-valued or complex-valued.
+       */
+      typedef ScalarType                scalar_type;
+
       static ScalarType
       get_directional_derivative(const ScalarType   &/*x*/,
                                  const unsigned int  /*direction*/)
-- 
2.39.5