Move result ConvexPolygon outside of the loop

Refs #12584
mantidproject · Jun 25, 2015 · aa38947 · aa38947
1 parent cb5c273
commit aa38947
Showing 1 changed file with 14 additions and 8 deletions.
diff --git a/Code/Mantid/Framework/Algorithms/src/Rebin2D.cpp b/Code/Mantid/Framework/Algorithms/src/Rebin2D.cpp
@@ -179,6 +179,9 @@ void Rebin2D::rebinToOutput(const Geometry::Quadrilateral &inputQ,
                              en_start, en_end))
     return;
 
+  // It seems to be more efficient to construct this once and clear it before each calculation
+  // in the loop
+  ConvexPolygon intersectOverlap;
   for (size_t qi = qstart; qi < qend; ++qi) {
     const double vlo = verticalAxis[qi];
     const double vhi = verticalAxis[qi + 1];
@@ -193,13 +196,13 @@ void Rebin2D::rebinToOutput(const Geometry::Quadrilateral &inputQ,
       if (boost::math::isnan(yValue)) {
         continue;
       }
-      ConvexPolygon overlap;
-      if(intersection(outputQ, inputQ, overlap)) {
-        const double weight = overlap.area() / inputQ.area();
+      intersectOverlap.clear();
+      if(intersection(outputQ, inputQ, intersectOverlap)) {
+        const double weight = intersectOverlap.area() / inputQ.area();
         yValue *= weight;
         double eValue = inputWS->readE(i)[j] * weight;
         if (inputWS->isDistribution()) {
-          const double overlapWidth = overlap.maxX() - overlap.minX();
+          const double overlapWidth = intersectOverlap.maxX() - intersectOverlap.minX();
           yValue *= overlapWidth;
           eValue *= overlapWidth;
         }
@@ -238,6 +241,9 @@ void Rebin2D::rebinToFractionalOutput(const Geometry::Quadrilateral &inputQ,
   // Don't do the overlap removal if already RebinnedOutput.
   // This wreaks havoc on the data.
   const bool removeOverlap(inputWS->isDistribution() && inputWS->id() != "RebinnedOutput");
+  // It seems to be more efficient to construct this once and clear it before each calculation
+  // in the loop
+  ConvexPolygon intersectOverlap;
   for (size_t qi = qstart; qi < qend; ++qi) {
     const double vlo = verticalAxis[qi];
     const double vhi = verticalAxis[qi + 1];
@@ -252,13 +258,13 @@ void Rebin2D::rebinToFractionalOutput(const Geometry::Quadrilateral &inputQ,
       if (boost::math::isnan(yValue)) {
         continue;
       }
-      ConvexPolygon overlap;
-      if(intersection(outputQ, inputQ, overlap)) {
-        const double weight = overlap.area() / inputQ.area();
+      intersectOverlap.clear();
+      if(intersection(outputQ, inputQ, intersectOverlap)) {
+        const double weight = intersectOverlap.area() / inputQ.area();
         yValue *= weight;
         double eValue = inputWS->readE(i)[j] * weight;
         if (removeOverlap) {
-          const double overlapWidth = overlap.maxX() - overlap.minX();
+          const double overlapWidth = intersectOverlap.maxX() - intersectOverlap.minX();
           yValue *= overlapWidth;
           eValue *= overlapWidth;
         }