Example usage for org.apache.commons.math3.stat.regression SimpleRegression getSumSquaredErrors

Introduction

In this page you can find the example usage for org.apache.commons.math3.stat.regression SimpleRegression getSumSquaredErrors.

Prototype

public double getSumSquaredErrors() 

Source Link

Document

Returns the <a href="http://www.xycoon.com/SumOfSquares.htm"> sum of squared errors</a> (SSE) associated with the regression model.

Usage

From source file:eu.tango.energymodeller.energypredictor.CpuOnlyEnergyPredictor.java

/**
 * This calculates the mathematical function that predicts the power
 * consumption given the cpu utilisation.
 *
 * @param host The host to get the function for
 * @return The mathematical function that predicts the power consumption
 * given the cpu utilisation./*from   w  w  w  .j  a  v  a2s.co  m*/
 */
private PredictorFunction<LinearFunction> retrieveModel(Host host) {
    if (modelCache.containsKey(host)) {
        /**
         * A small cache avoids recalculating the regression so often.
         */
        return modelCache.get(host);
    }
    LinearFunction model = new LinearFunction();
    SimpleRegression regressor = new SimpleRegression(true);
    for (HostEnergyCalibrationData data : host.getCalibrationData()) {
        regressor.addData(data.getCpuUsage(), data.getWattsUsed());
    }
    model.setIntercept(regressor.getIntercept());
    model.setCoefficient(regressor.getSlope());
    PredictorFunction<LinearFunction> answer = new PredictorFunction<>(model, regressor.getSumSquaredErrors(),
            Math.sqrt(regressor.getMeanSquareError()));
    modelCache.put(host, answer);
    return answer;
}

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