Time: Increase the precision the value entry is written in uniform/time

Add check for round-off error causing time reversal
Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=815

src/OpenFOAM/db/Time/Time.C

@@ -732,11 +732,11 @@ void Foam::Time::setUnmodified(const label watchFd) const
 }
 
 
-Foam::word Foam::Time::timeName(const scalar t)
+Foam::word Foam::Time::timeName(const scalar t, const int precision)
 {
     std::ostringstream buf;
     buf.setf(ios_base::fmtflags(format_), ios_base::floatfield);
-    buf.precision(precision_);
+    buf.precision(precision);
     buf << t;
     return buf.str();
 }
@@ -1137,10 +1137,26 @@ Foam::Time& Foam::Time::operator++()
                 WarningIn("Time::operator++()")
                     << "Current time name " << dimensionedScalar::name()
                     << " is the old as the previous one " << oldTimeName
-                    << endl
+                    << nl
                     << "    This might result in overwriting old results."
                     << endl;
             }
+
+            // Check if round-off error caused time-reversal
+            scalar oldTimeNameValue = -VGREAT;
+            if
+            (
+                readScalar(oldTimeName.c_str(), oldTimeNameValue)
+             && (sign(timeNameValue - oldTimeNameValue) != sign(deltaT_))
+            )
+            {
+                WarningIn("Time::operator++()")
+                    << "Current time name " << dimensionedScalar::name()
+                    << " is set to an instance prior to the previous one "
+                    << oldTimeName << nl
+                    << "    This might result in temporal discontinuities."
+                    << endl;
+            }
         }
     }
 

src/OpenFOAM/db/Time/Time.H

@@ -406,7 +406,12 @@ public:
         // Access
 
             //- Return time name of given scalar time
-            static word timeName(const scalar);
+            //  formatted with given precision
+            static word timeName
+            (
+                const scalar,
+                const int precision = precision_
+            );
 
             //- Return current time name
             virtual word timeName() const;

src/OpenFOAM/db/Time/TimeIO.C

@@ -508,7 +508,7 @@ bool Foam::Time::writeObject
             )
         );
 
-        timeDict.add("value", timeToUserTime(value()));
+        timeDict.add("value", timeName(timeToUserTime(value()), maxPrecision_));
         timeDict.add("name", string(tmName));
         timeDict.add("index", timeIndex_);
         timeDict.add("deltaT", timeToUserTime(deltaT_));