work around scotch fpe bug

applications/utilities/parallelProcessing/decomposePar/decomposeParDict

@@ -55,7 +55,17 @@ metisCoeffs
 }
 
 scotchCoeffs
-{}
+{
+    //processorWeights
+    //(
+    //    1
+    //    1
+    //    1
+    //    1
+    //);
+    //writeGraph  true;
+    //strategy "b";
+}
 
 manualCoeffs
 {

src/decompositionMethods/decompositionMethods/scotchDecomp/scotchDecomp.C

@@ -75,6 +75,24 @@ extern "C"
 }
 
 
+// Hack: scotch generates floating point errors so need to switch of error
+//       trapping!
+#if defined(linux) || defined(linuxAMD64) || defined(linuxIA64)
+#    define LINUX
+#endif
+
+#if defined(LINUX) && defined(__GNUC__)
+#    define LINUX_GNUC
+#endif
+
+#ifdef LINUX_GNUC
+#   ifndef __USE_GNU
+#       define __USE_GNU
+#   endif
+#   include <fenv.h>
+#endif
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
@@ -113,13 +131,30 @@ Foam::label Foam::scotchDecomp::decompose
 {
     // Strategy
     // ~~~~~~~~
+
     // Default.
     SCOTCH_Strat stradat;
     check(SCOTCH_stratInit(&stradat), "SCOTCH_stratInit");
-    //SCOTCH_stratGraphMap(&stradat, &argv[i][2]);
-    //fprintf(stdout, "S\tStrat=");
-    //SCOTCH_stratSave(&stradat, stdout);
-    //fprintf(stdout, "\n");
+
+    if (decompositionDict_.found("scotchCoeffs"))
+    {
+        const dictionary& scotchCoeffs =
+            decompositionDict_.subDict("scotchCoeffs");
+
+
+        string strategy;
+        if (scotchCoeffs.readIfPresent("strategy", strategy))
+        {
+            if (debug)
+            {
+                Info<< "scotchDecomp : Using strategy " << strategy << endl;
+            }
+            SCOTCH_stratGraphMap(&stradat, strategy.c_str());
+            //fprintf(stdout, "S\tStrat=");
+            //SCOTCH_stratSave(&stradat, stdout);
+            //fprintf(stdout, "\n");
+        }
+    }
 
 
     // Graph
@@ -198,12 +233,36 @@ Foam::label Foam::scotchDecomp::decompose
 
     SCOTCH_Arch archdat;
     check(SCOTCH_archInit(&archdat), "SCOTCH_archInit");
-    check
-    (
-        // SCOTCH_archCmpltw for weighted.
-        SCOTCH_archCmplt(&archdat, nProcessors_),
-        "SCOTCH_archCmplt"
-    );
+
+    List<label> processorWeights;
+    if (decompositionDict_.found("scotchCoeffs"))
+    {
+        const dictionary& scotchCoeffs =
+            decompositionDict_.subDict("scotchCoeffs");
+
+        scotchCoeffs.readIfPresent("processorWeights", processorWeights);
+    }
+    if (processorWeights.size())
+    {
+        if (debug)
+        {
+            Info<< "scotchDecomp : Using procesor weights " << processorWeights
+                << endl;
+        }
+        check
+        (
+            SCOTCH_archCmpltw(&archdat, nProcessors_, processorWeights.begin()),
+            "SCOTCH_archCmpltw"
+        );
+    }
+    else
+    {
+        check
+        (
+            SCOTCH_archCmplt(&archdat, nProcessors_),
+            "SCOTCH_archCmplt"
+        );
+    }
 
 
     //SCOTCH_Mapping mapdat;
@@ -212,6 +271,16 @@ Foam::label Foam::scotchDecomp::decompose
     //SCOTCH_graphMapExit(&grafdat, &mapdat);
 
 
+    // Hack:switch off fpu error trapping
+#   ifdef LINUX_GNUC
+    int oldExcepts = fedisableexcept
+    (
+        FE_DIVBYZERO
+      | FE_INVALID
+      | FE_OVERFLOW
+    );
+#   endif
+
     finalDecomp.setSize(xadj.size()-1);
     finalDecomp = 0;
     check
@@ -226,6 +295,11 @@ Foam::label Foam::scotchDecomp::decompose
         "SCOTCH_graphMap"
     );
 
+#   ifdef LINUX_GNUC
+    feenableexcept(oldExcepts);
+#   endif
+
+
 
     //finalDecomp.setSize(xadj.size()-1);
     //check