private static double euclidean()

in commons-numbers-core/src/main/java/org/apache/commons/numbers/core/Norm.java [264:319]
41 lines of code
6 McCabe index (conditional complexity)

    private static double euclidean(final double x,
                                    final double y) {
        final double xabs = Math.abs(x);
        final double yabs = Math.abs(y);

        final double max;
        final double min;
        // the compare method considers NaN greater than other values, meaning that our
        // check for if the max is finite later on will detect NaNs correctly
        if (Double.compare(xabs, yabs) > 0) {
            max = xabs;
            min = yabs;
        } else {
            max = yabs;
            min = xabs;
        }

        // if the max is not finite, then one of the inputs must not have
        // been finite
        if (!Double.isFinite(max)) {
            // let the standard multiply operation determine whether to return NaN or infinite
            return xabs * yabs;
        } else if (Math.getExponent(max) - Math.getExponent(min) > EXP_DIFF_THRESHOLD_2D) {
            // value is completely dominated by max; just return max
            return max;
        }

        // compute the scale and rescale values
        final double scale;
        final double rescale;
        if (max > LARGE_THRESH) {
            scale = SCALE_DOWN;
            rescale = SCALE_UP;
        } else if (max < SAFE_SCALE_UP_THRESH) {
            scale = SCALE_UP;
            rescale = SCALE_DOWN;
        } else {
            scale = 1d;
            rescale = 1d;
        }

        // initialise sum and compensation using scaled x
        final double sx = xabs * scale;
        double sum = sx * sx;
        double comp = DD.twoSquareLow(sx, sum);

        // add scaled y
        final double sy = yabs * scale;
        final double py = sy * sy;
        comp += DD.twoSquareLow(sy, py);
        final double sumPy = sum + py;
        comp += DD.twoSumLow(sum, py, sumPy);
        sum = sumPy;

        return Math.sqrt(sum + comp) * rescale;
    }