MathUtils.java

package edu.stanford.hci.r3.util;

public class MathUtils {

        public static double average(double... vals) {
                if (vals == null || vals.length == 0) {
                        return 0;
                }
                return sum(vals) / vals.length;
        }

        public static double distance(double x1, double y1, double x2, double y2) {
                return Math.sqrt(Math.pow(x1 - x2, 2) + Math.pow(y1 - y2, 2));
        }

        public static int rint(double val) {
                return (int) Math.round(val);
        }

        public static double standardDeviation(double... vals) {
                if (vals == null || vals.length == 0) {
                        return 0;
                }

                final double mean = average(vals);
                double variance = 0;
                for (double val : vals) {
                        variance += Math.pow((val - mean), 2);
                }
                return Math.sqrt(variance / vals.length);
        }

        public static double standardDeviation(Double... vals) {
                double[] valsArray = new double[vals.length];
                for (int i = 0; i < valsArray.length; i++) {
                        valsArray[i] = vals[i];
                }
                return standardDeviation(valsArray);
        }

        private static double sum(double... vals) {
                double sum = 0;
                for (double val : vals) {
                        sum += val;
                }
                return sum;
        }
}

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