/// <summary>
/// This function return the cummulative distribution function (CDF)
/// for ChiSquare Distribution where X2 from 0 t x2 and
/// number degree of freedom k.
/// </summary>
/// <param name="x2">double. x2</param>
/// <param name="k">int. k is number degree of freedom</param>
/// <returns>
/// The value of cummulative distribution function (CDF)
/// for ChiSquare Distribution where X2 form 0 t x2 and
/// number degree of freedom k.
/// </returns>
public static double CDF(double x2, int k)
{
// the number degree of freedom must be
// more or equal than 1. The value of x must be
// not less than 0
if (k < 1 || x2 < 0) return double.NaN;
ChiSquareFunction function = new ChiSquareFunction(k);
return Integrator.GaussLegendre(function, 0, x2, 1.0e-6);
}
/// <summary>
/// This function return the probability density function (PDF)
/// for ChiSquare Distribution for X2=x2 and
/// number degree of freedom k.
/// </summary>
/// <param name="x2">double. x2</param>
/// <param name="k">int. k is number degree of freedom</param>
/// <returns>
/// The value of probability distribution function (PDF)
/// for ChiSquare Distribution for X2=x2 and
/// number degree of freedom k.
/// </returns>
private static double PDF(double x2, int k)
{
// the number degree of freedom must be
// more or equal than 1. The value of x must be
// not less than 0
if (k < 1 || x2 < 0)
{
return(double.NaN);
}
ChiSquareFunction function = new ChiSquareFunction(k);
return(function.Value(x2));
}
/// <summary>
/// This function return the cummulative distribution function (CDF)
/// for ChiSquare Distribution where X2 from 0 t x2 and
/// number degree of freedom k.
/// </summary>
/// <param name="x2">double. x2</param>
/// <param name="k">int. k is number degree of freedom</param>
/// <returns>
/// The value of cummulative distribution function (CDF)
/// for ChiSquare Distribution where X2 form 0 t x2 and
/// number degree of freedom k.
/// </returns>
public static double CDF(double x2, int k)
{
// the number degree of freedom must be
// more or equal than 1. The value of x must be
// not less than 0
if (k < 1 || x2 < 0)
{
return(double.NaN);
}
ChiSquareFunction function = new ChiSquareFunction(k);
return(Integrator.GaussLegendre(function, 0, x2, 1.0e-6));
}
/// <summary>
/// This function return the probability density function (PDF)
/// for ChiSquare Distribution for X2=x2 and
/// number degree of freedom k.
/// </summary>
/// <param name="x2">double. x2</param>
/// <param name="k">int. k is number degree of freedom</param>
/// <returns>
/// The value of probability distribution function (PDF)
/// for ChiSquare Distribution for X2=x2 and
/// number degree of freedom k.
/// </returns>
private static double PDF(double x2, int k)
{
// the number degree of freedom must be
// more or equal than 1. The value of x must be
// not less than 0
if (k < 1 || x2 < 0) return double.NaN;
ChiSquareFunction function = new ChiSquareFunction(k);
return function.Value(x2);
}