private static double sfExact()

in commons-statistics-inference/src/main/java/org/apache/commons/statistics/inference/KolmogorovSmirnovDistribution.java [765:791]

• 19 lines of code
• 7 McCabe index (conditional complexity)

        private static double sfExact(double x, int n) {
            if (n * x * x >= 372.5 || x >= 1) {
                // p would underflow, or x is out of the domain
                return 0;
            }
            if (x <= 0) {
                // edge-of, or out-of, the domain
                return 1;
            }
            if (n == 1) {
                return x;
            }
            // x <= 1/n
            // [1] Equation (33)
            final double nx = n * x;
            if (nx <= 1) {
                // 1 - x (1+x)^(n-1): here x may be small so use log1p
                return 1 - x * Math.exp((n - 1) * Math.log1p(x));
            }
            // 1 - 1/n <= x < 1
            // [1] Equation (16)
            if (n - 1 <= nx) {
                // (1-x)^n: here x > 0.5 and 1-x is exact
                return Math.pow(1 - x, n);
            }
            return -1;
        }