69 lines
1.6 KiB
C++
69 lines
1.6 KiB
C++
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/*==============================================================================
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Copyright 2018 by Roland Rabien, 1998 David C. Swaim
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For more information visit www.rabiensoftware.com
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==============================================================================*/
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LinearRegression::LinearRegression()
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{
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}
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LinearRegression::LinearRegression (Array<juce::Point<double>> points)
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{
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for (auto p : points)
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addPoint (p);
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calculate();
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}
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void LinearRegression::clear()
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{
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n = 0;
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sumX = 0;
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sumY = 0;
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sumXsquared = 0;
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sumYsquared = 0;
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sumXY = 0;
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a = 0;
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b = 0;
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coefD = 0;
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coefC = 0;
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stdError = 0;
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}
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void LinearRegression::addPoint (juce::Point<double> pnt)
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{
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n++;
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sumX += pnt.getX();
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sumY += pnt.getY();
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sumXsquared += pnt.getX() * pnt.getX();
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sumYsquared += pnt.getY() * pnt.getY();
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sumXY += pnt.getX() * pnt.getY();
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}
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void LinearRegression::calculate()
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{
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if (haveData())
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{
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if (std::fabs (n * sumXsquared - sumX * sumX) > DBL_EPSILON)
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{
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b = (n * sumXY - sumY * sumX) / (n * sumXsquared - sumX * sumX);
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a = (sumY - b * sumX) / n;
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double sx = b * (sumXY - sumX * sumY / n);
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double sy2 = sumYsquared - sumY * sumY / n;
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double sy = sy2 - sx;
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coefD = sx / sy2;
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coefC = std::sqrt (coefD);
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stdError = std::sqrt(sy / (n - 2));
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}
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else
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{
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a = b = coefD = coefC = stdError = 0.0;
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}
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}
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}
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