/// <summary> /// Gets the cumulative distribution function (cdf) for /// the this distribution evaluated at point <c>x</c>. /// </summary> /// /// <param name="x">A single point in the distribution range.</param> /// /// <remarks> /// The Cumulative Distribution Function (CDF) describes the cumulative /// probability that a given value or any value smaller than it will occur. /// </remarks> /// public override double DistributionFunction(double x) { double v = DegreesOfFreedom; double sqrt = Math.Sqrt(x * x + v); double u = (x + sqrt) / (2 * sqrt); return(Special.Ibeta(v / 2.0, v / 2.0, u)); }
/// <summary> /// Gets the cumulative distribution function (cdf) for /// the F-distribution evaluated at point <c>x</c>. /// </summary> /// /// <param name="x">A single point in the distribution range.</param> /// /// <remarks> /// The Cumulative Distribution Function (CDF) describes the cumulative /// probability that a given value or any value smaller than it will occur. /// </remarks> /// public override double DistributionFunction(double x) { double u = (d1 * x) / (d1 * x + d2); return(Special.Ibeta(d1 * 0.5, d2 * 0.5, u)); }