private int computeInverseProbability()

in commons-statistics-distribution/src/main/java/org/apache/commons/statistics/distribution/HypergeometricDistribution.java [320:352]

• 20 lines of code
• 6 McCabe index (conditional complexity)

    private int computeInverseProbability(double p, double q, boolean complement) {
        if (p == 0) {
            return lowerBound;
        }
        if (q == 0) {
            return upperBound;
        }

        // Sum the PDF(x) until the appropriate p-value is obtained
        // CDF: require smallest x where P(X<=x) >= p
        // SF:  require smallest x where P(X>x) <= q
        // The choice of summation uses the mid-point.
        // The test on the CDF or SF is based on the appropriate input p-value.

        final double[] mid = getMidPoint();
        final int m = (int) mid[0];
        final double mp = mid[1];

        final int midPointComparison = complement ?
            Double.compare(1 - mp, q) :
            Double.compare(p, mp);

        if (midPointComparison < 0) {
            return inverseLower(p, q, complement);
        } else if (midPointComparison > 0) {
            // Avoid floating-point summation error when the mid-point computed using the
            // lower sum is different to the midpoint computed using the upper sum.
            // Here we know the result must be above the midpoint so we can clip the result.
            return Math.max(m + 1, inverseUpper(p, q, complement));
        }
        // Exact mid-point
        return m;
    }