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fdo#75538 R^2 calculation for trendline similar to LINEST function

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Modify for forced intercept of trendline, calculation of R^2 in the same
way as LINEST function does calculation

Change-Id: Ic943b1ca1bbe30b1a4b88e2a338eb9dc34d848b6
Reviewed-on: https://gerrit.libreoffice.org/8402
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
Tested-by: Tomaž Vajngerl <quikee@gmail.com>
This commit is contained in:
Laurent Balland-Poirier
2014-03-01 00:20:53 +01:00
committed by Tomaž Vajngerl
parent 6a71b8d902
commit 00cb825ab3
1 changed files with 3 additions and 5 deletions
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8
chart2/source/tools/PolynomialRegressionCurveCalculator.cxx
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@@ -168,7 +168,6 @@ void SAL_CALL PolynomialRegressionCurveCalculator::recalculateRegression(
double aSumError = 0.0; double aSumError = 0.0;
double aSumTotal = 0.0; double aSumTotal = 0.0;
double aSumYpred2 = 0.0; double aSumYpred2 = 0.0;
double aSumYactual2 = 0.0;
for( sal_Int32 i = 0; i < aNoValues; i++ ) for( sal_Int32 i = 0; i < aNoValues; i++ )
{ {
@@ -177,15 +176,14 @@ void SAL_CALL PolynomialRegressionCurveCalculator::recalculateRegression(
double yPredicted = getCurveValue( xValue ); double yPredicted = getCurveValue( xValue );
aSumTotal += (yActual - yAverage) * (yActual - yAverage); aSumTotal += (yActual - yAverage) * (yActual - yAverage);
aSumError += (yActual - yPredicted) * (yActual - yPredicted); aSumError += (yActual - yPredicted) * (yActual - yPredicted);
aSumYpred2 += yPredicted * yPredicted; if(mForceIntercept)
aSumYactual2 += yActual * yActual; aSumYpred2 += (yPredicted - mInterceptValue) * (yPredicted - mInterceptValue);
} }
double aRSquared = 0.0; double aRSquared = 0.0;
if(mForceIntercept) if(mForceIntercept)
{ {
if(aSumYactual2 != 0.0) aRSquared = aSumYpred2 / (aSumError + aSumYpred2);
aRSquared = aSumYpred2 / aSumYactual2;
} }
else else
{ {