From 552c1f928f29e86e17cc404deeba90d24574aec7 Mon Sep 17 00:00:00 2001
From: Timo Heister <timo.heister@gmail.com>
Date: Wed, 30 Sep 2015 13:39:35 -0400
Subject: [PATCH] add support for pow(a,b) in FunctionParser

it turns out muparser only supports "a^b" out of the box, so we add
"pow(a,b)" as a custom function.
---
 doc/news/changes.h                                      | 5 +++++
 source/base/function_parser.cc                          | 9 ++++++++-
 tests/base/function_parser_06.cc                        | 1 +
 tests/base/function_parser_06.with_muparser=true.output | 1 +
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/doc/news/changes.h b/doc/news/changes.h
index 4763589e90..3ad05671c4 100644
--- a/doc/news/changes.h
+++ b/doc/news/changes.h
@@ -159,6 +159,11 @@ inconvenience this causes.
 <a name="general"></a>
 <h3>General</h3>
 <ol>
+  <li> New: FunctionParser now supports pow(a,b).
+  <br>
+  (Timo Heister, 2015/09/30)
+  </li>
+
   <li> New: MGTransferPrebuilt can now be used with parallel::distributed::Vector
   and TrilinosWrappers::SparseMatrix as a transfer matrix.
   <br>
diff --git a/source/base/function_parser.cc b/source/base/function_parser.cc
index 61aef60acf..25ffd17e81 100644
--- a/source/base/function_parser.cc
+++ b/source/base/function_parser.cc
@@ -165,6 +165,11 @@ namespace internal
   {
     return log(value);
   }
+
+  double mu_pow(double a, double b)
+  {
+    return std::pow(a, b);
+  }
 }
 
 
@@ -202,6 +207,7 @@ void FunctionParser<dim>:: init_muparser() const
       fp.get()[component].DefineFun("floor", internal::mu_floor, true);
       fp.get()[component].DefineFun("sec", internal::mu_sec, true);
       fp.get()[component].DefineFun("log", internal::mu_log, true);
+      fp.get()[component].DefineFun("pow", internal::mu_pow, true);
 
       try
         {
@@ -250,7 +256,8 @@ void FunctionParser<dim>:: init_muparser() const
             "cot",
             "csc",
             "floor",
-            "sec"
+            "sec",
+            "pow"
           };
           for (unsigned int f=0; f<sizeof(function_names)/sizeof(function_names[0]); ++f)
             {
diff --git a/tests/base/function_parser_06.cc b/tests/base/function_parser_06.cc
index 31c2a1e044..816641f90d 100644
--- a/tests/base/function_parser_06.cc
+++ b/tests/base/function_parser_06.cc
@@ -96,6 +96,7 @@ void test()
   eval("sqrt(0.5)",Point<2>(0,0), sqrt(0.5));
   eval("tan(0.5)",Point<2>(0,0), tan(0.5));
   eval("tanh(0.5)",Point<2>(0,0), tanh(0.5));
+  eval("pow (9.0, 0.5)",Point<2>(0,0), 3.0);
 
 
 }
diff --git a/tests/base/function_parser_06.with_muparser=true.output b/tests/base/function_parser_06.with_muparser=true.output
index 2ec9e6652b..41caadd752 100644
--- a/tests/base/function_parser_06.with_muparser=true.output
+++ b/tests/base/function_parser_06.with_muparser=true.output
@@ -35,3 +35,4 @@ DEAL::'sinh(0.5)' @ 0.00000 0.00000 is 0.521095 ( expected 0.521095 )
 DEAL::'sqrt(0.5)' @ 0.00000 0.00000 is 0.707107 ( expected 0.707107 )
 DEAL::'tan(0.5)' @ 0.00000 0.00000 is 0.546302 ( expected 0.546302 )
 DEAL::'tanh(0.5)' @ 0.00000 0.00000 is 0.462117 ( expected 0.462117 )
+DEAL::'pow (9.0, 0.5)' @ 0.00000 0.00000 is 3.00000 ( expected 3.00000 )
-- 
2.39.5