[Libreoffice-commits] core.git: sc/source

[dante (via logerrit)]

 sc/source/core/tool/interpr3.cxx |   30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

New commits:
commit 9d7db2b4f09e08a607c8f07db38afa722d98a84f
Author:     dante <dante19031999 at gmail.com>
AuthorDate: Sat May 1 01:23:41 2021 +0200
Commit:     Mike Kaganski <mike.kaganski at collabora.com>
CommitDate: Mon May 3 13:49:42 2021 +0200

    tdf#137679 Use kahan summation for ScInterpreter::CalculatePearsonCovar
    
    Change-Id: Ia268415c0fa5c26476cdf328e2f8863e97600167
    Reviewed-on: https://gerrit.libreoffice.org/c/core/+/114951
    Tested-by: Jenkins
    Reviewed-by: Mike Kaganski <mike.kaganski at collabora.com>

diff --git a/sc/source/core/tool/interpr3.cxx b/sc/source/core/tool/interpr3.cxx
index d41f4f98b475..193a9ca4b553 100644
--- a/sc/source/core/tool/interpr3.cxx
+++ b/sc/source/core/tool/interpr3.cxx
@@ -4557,8 +4557,8 @@ void ScInterpreter::CalculatePearsonCovar( bool _bPearson, bool _bStexy, bool _b
      * for example above 10^8
      */
     double fCount           = 0.0;
-    double fSumX            = 0.0;
-    double fSumY            = 0.0;
+    KahanSum fSumX          = 0.0;
+    KahanSum fSumY          = 0.0;
 
     for (SCSIZE i = 0; i < nC1; i++)
     {
@@ -4566,10 +4566,8 @@ void ScInterpreter::CalculatePearsonCovar( bool _bPearson, bool _bStexy, bool _b
         {
             if (!pMat1->IsStringOrEmpty(i,j) && !pMat2->IsStringOrEmpty(i,j))
             {
-                double fValX = pMat1->GetDouble(i,j);
-                double fValY = pMat2->GetDouble(i,j);
-                fSumX += fValX;
-                fSumY += fValY;
+                fSumX += pMat1->GetDouble(i,j);
+                fSumY += pMat2->GetDouble(i,j);
                 fCount++;
             }
         }
@@ -4578,11 +4576,11 @@ void ScInterpreter::CalculatePearsonCovar( bool _bPearson, bool _bStexy, bool _b
         PushNoValue();
     else
     {
-        double fSumDeltaXDeltaY = 0.0; // sum of (ValX-MeanX)*(ValY-MeanY)
-        double fSumSqrDeltaX    = 0.0; // sum of (ValX-MeanX)^2
-        double fSumSqrDeltaY    = 0.0; // sum of (ValY-MeanY)^2
-        const double fMeanX = fSumX / fCount;
-        const double fMeanY = fSumY / fCount;
+        KahanSum fSumDeltaXDeltaY = 0.0; // sum of (ValX-MeanX)*(ValY-MeanY)
+        KahanSum fSumSqrDeltaX    = 0.0; // sum of (ValX-MeanX)^2
+        KahanSum fSumSqrDeltaY    = 0.0; // sum of (ValY-MeanY)^2
+        const double fMeanX = fSumX.get() / fCount;
+        const double fMeanY = fSumY.get() / fCount;
         for (SCSIZE i = 0; i < nC1; i++)
         {
             for (SCSIZE j = 0; j < nR1; j++)
@@ -4607,17 +4605,17 @@ void ScInterpreter::CalculatePearsonCovar( bool _bPearson, bool _bStexy, bool _b
                 || (!_bStexy && fSumSqrDeltaY < ::std::numeric_limits<double>::min()))
                 PushError( FormulaError::DivisionByZero);
             else if ( _bStexy )
-                PushDouble( sqrt( (fSumSqrDeltaY - fSumDeltaXDeltaY *
-                            fSumDeltaXDeltaY / fSumSqrDeltaX) / (fCount-2)));
+                PushDouble( sqrt( ( fSumSqrDeltaY - fSumDeltaXDeltaY.get() *
+                            fSumDeltaXDeltaY.get() / fSumSqrDeltaX.get() ).get() / (fCount-2)));
             else
-                PushDouble( fSumDeltaXDeltaY / sqrt( fSumSqrDeltaX * fSumSqrDeltaY));
+                PushDouble( fSumDeltaXDeltaY.get() / sqrt( fSumSqrDeltaX.get() * fSumSqrDeltaY.get() ));
         }
         else
         {
             if ( _bSample )
-                PushDouble( fSumDeltaXDeltaY / ( fCount - 1 ) );
+                PushDouble( fSumDeltaXDeltaY.get() / ( fCount - 1 ) );
             else
-                PushDouble( fSumDeltaXDeltaY / fCount);
+                PushDouble( fSumDeltaXDeltaY.get() / fCount);
         }
     }
 }