From 7fc61d7eb7d46d601ec3aa2ffab3022ec59e80df Mon Sep 17 00:00:00 2001
From: Will Bainbridge <http://cfd.direct>
Date: Tue, 18 Dec 2018 11:51:45 +0000
Subject: [PATCH] negEntry: Supporting negation of already negative quantities

---
 .../functionEntries/negEntry/negEntry.C           | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/OpenFOAM/db/dictionary/functionEntries/negEntry/negEntry.C b/src/OpenFOAM/db/dictionary/functionEntries/negEntry/negEntry.C
index 698bb0be9a..7607c7a66c 100644
--- a/src/OpenFOAM/db/dictionary/functionEntries/negEntry/negEntry.C
+++ b/src/OpenFOAM/db/dictionary/functionEntries/negEntry/negEntry.C
@@ -85,11 +85,20 @@ Foam::string Foam::functionEntries::negEntry::negateVariable
     {
         const token variable(ePtr->stream());
 
-        // Negate variable
+        // Convert to a string
         OStringStream os(is.format());
-        os << '-' << variable;
+        os << variable;
+        const string str(os.str());
 
-        return os.str();
+        // Negate
+        if (str[0] == '-')
+        {
+            return str(1, str.size() - 1);
+        }
+        else
+        {
+            return '-' + str;
+        }
     }
     else
     {