ENH: Prefer multiplication to division

Multiplication is more efficient than division, so use multiply by reciprical to make 1 division.
InsightSoftwareConsortium · Apr 13, 2020 · 50b91ab · 50b91ab
1 parent 8626163
commit 50b91ab
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/Modules/Registration/Metricsv4/include/itkMattesMutualInformationImageToImageMetricv4.hxx b/Modules/Registration/Metricsv4/include/itkMattesMutualInformationImageToImageMetricv4.hxx
@@ -347,9 +347,10 @@ MattesMutualInformationImageToImageMetricv4<TFixedImage,
   {
     itkExceptionMacro("Fixed image marginal PDF summed to zero");
   }
+  const PDFValueType inv_totalMassOfPDF = 1.0 / totalMassOfPDF;
   for (unsigned int bin = 0; bin < this->m_NumberOfHistogramBins; ++bin)
   {
-    this->m_ThreaderFixedImageMarginalPDF[0][bin] /= totalMassOfPDF;
+    this->m_ThreaderFixedImageMarginalPDF[0][bin] *= inv_totalMassOfPDF;
   }
 
   static constexpr PDFValueType closeToZero = std::numeric_limits<PDFValueType>::epsilon();