/// <summary>
/// Returns the matrix of interpolation coefficients.
/// </summary>
/// <param name="points">Number of points</param>
/// <returns>Matrix</returns>
public static float[,] GetCoefficients(int points)
{
// Compute difference coefficient table
float fac = Special.Factorial(points);
float[,] deltas = new float[points, points];
float h, delta;
int j, k;
// do job
for (j = 0; j < points; j++)
{
h = 1.0f;
delta = j;
for (k = 0; k < points; k++)
{
deltas[j, k] = h / Special.Factorial(k);
h *= delta;
}
}
// matrix invert
deltas = Matrice.Invert(deltas);
//// rounding
//for (j = 0; j < points; j++)
// for (k = 0; k < points; k++)
// deltas[j, k] = (Math.Round(deltas[j, k] * fac, MidpointRounding.AwayFromZero)) / fac;
return(deltas);
}
/// <summary>
/// Creates the interpolation coefficients.
/// </summary>
/// <param name="points">The number of points in the tableau.</param>
///
private static double[][,] createInterpolationCoefficients(int points)
{
// Compute difference coefficient table
double[][,] c = new double[points][, ];
double fac = Special.Factorial(points);
for (int i = 0; i < points; i++)
{
double[,] deltas = new double[points, points];
for (int j = 0; j < points; j++)
{
double h = 1.0;
double delta = j - i;
for (int k = 0; k < points; k++)
{
deltas[j, k] = h / Special.Factorial(k);
h *= delta;
}
}
c[i] = Matrix.Inverse(deltas);
for (int j = 0; j < points; j++)
{
for (int k = 0; k < points; k++)
{
c[i][j, k] = (Math.Round(c[i][j, k] * fac, MidpointRounding.AwayFromZero)) / fac;
}
}
}
return(c);
}
/// <summary>
/// Initializes a new instance of the <see cref="MultinomialDistribution"/> class.
/// </summary>
/// <param name="numberOfTrials">The total number of trials N.</param>
/// <param name="probabilities">A vector containing the probabilities of seeing each of possible outcomes.</param>
public MultinomialDistribution(int numberOfTrials, params double[] probabilities)
: base(probabilities.Length)
{
N = numberOfTrials;
this.probabilities = probabilities;
nfac = Special.Factorial(numberOfTrials);
}
/// <summary>
/// Returns the value of the probability density function.
/// </summary>
/// <param name="x">Value</param>
/// <returns>float precision floating point number</returns>
public float Function(float x)
{
if (x < 0)
{
return(0);
}
return((float)Math.Exp(-l) * (float)Math.Pow(l, x) / Special.Factorial(x));
}
/// <summary>
/// Returns the value of the probability distribution function.
/// </summary>
/// <param name="x">Value</param>
/// <returns>float precision floating point number</returns>
public float Distribution(float x)
{
if (x < 0)
{
return(float.NaN);
}
return(Special.GammaIncomplete(k, lambda * x) / Special.Factorial(k - 1));
}
/// <summary>
/// Returns the value of the wavelet function.
/// </summary>
/// <param name="x">Argument</param>
/// <returns>Function</returns>
public float Wavelet(float x)
{
if (x < 0)
{
return(0);
}
return((x - n) / Special.Factorial(n) * (float)Math.Pow(x, n - 1) * (float)Math.Exp(-x));
}
private void createCoefficients(int degree)
{
coefficients = new double[degree];
for (int i = 0; i < coefficients.Length; i++)
{
coefficients[i] = Math.Sqrt(Math.Pow(2 * gaussian.Gamma, i + 1) / Special.Factorial(i + 1));
}
}
/// <summary>
/// Gets the probability mass function (pmf) for
/// this distribution evaluated at point <c>x</c>.
/// </summary>
///
/// <param name="k">
/// A single point in the distribution range.</param>
///
/// <remarks>
/// The Probability Mass Function (PMF) describes the
/// probability that a given value <c>k</c> will occur.
/// </remarks>
///
/// <returns>
/// The probability of <c>x</c> occurring
/// in the current distribution.</returns>
///
public override double ProbabilityMassFunction(int k)
{
if (k < 0)
{
return(0);
}
return((Math.Pow(lambda, k) / Special.Factorial(k)) * epml);
}
/// <summary>
/// Gets the probability mass function (pmf) for
/// this distribution evaluated at point <c>x</c>.
/// </summary>
/// <param name="x">A single point in the distribution range.</param>
/// <returns>
/// The probability of <c>x</c> occurring
/// in the current distribution.
/// </returns>
/// <remarks>
/// The Probability Mass Function (PMF) describes the
/// probability that a given value <c>x</c> will occur.
/// </remarks>
public override double ProbabilityMassFunction(int[] x)
{
double theta = 1.0;
double prod = 1.0;
for (int i = 0; i < x.Length; i++)
{
theta *= Special.Factorial(x[i]);
prod *= System.Math.Pow(probabilities[i], x[i]);
}
return((nfac / theta) * prod);
}
public void FactorialTest()
{
int n = 3;
double expected = 6;
double actual = Special.Factorial(n);
Assert.AreEqual(expected, actual);
n = 35;
expected = 1.033314796638614e+40;
actual = Special.Factorial(n);
Assert.AreEqual(expected, actual, 1e27);
}
/// <summary>
///
/// </summary>
/// <param name="l"></param>
/// <returns></returns>
private float Row(float l)
{
float sum = 0;
int k, n = 20;
float fac;
for (k = 0; k < n; k++)
{
fac = Special.Factorial(k);
sum += (float)Math.Pow(l, k) * (float)Math.Log(fac) / fac;
}
return(sum);
}
/// <summary>
/// Gets the cumulative distribution function (cdf) for
/// this distribution evaluated at point <c>k</c>.
/// </summary>
///
/// <param name="k">
/// 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(int k)
{
if (k < 0)
{
return(0);
}
if (k >= Int32.MaxValue)
{
return(1);
}
return(Gamma.LowerIncomplete(k + 1, lambda) / Special.Factorial(k));
}
/// <summary>
/// Creates the interpolation coefficient table for interpolated numerical differentation.
/// </summary>
///
/// <param name="numberOfPoints">The number of points in the tableau.</param>
///
public static double[][,] CreateCoefficients(int numberOfPoints)
{
if (numberOfPoints % 2 != 1)
{
throw new ArgumentException("The number of points must be odd.", "numberOfPoints");
}
// Compute difference coefficient table
double[][,] c = new double[numberOfPoints][, ]; // [center][order, i];
double fac = Special.Factorial(numberOfPoints);
for (int i = 0; i < numberOfPoints; i++)
{
var deltas = new double[numberOfPoints, numberOfPoints];
for (int j = 0; j < numberOfPoints; j++)
{
double h = 1.0;
double delta = j - i;
for (int k = 0; k < numberOfPoints; k++)
{
deltas[j, k] = h / Special.Factorial(k);
h *= delta;
}
}
c[i] = Matrix.Inverse(deltas);
for (int j = 0; j < numberOfPoints; j++)
{
for (int k = 0; k < numberOfPoints; k++)
{
c[i][j, k] = (Math.Round(c[i][j, k] * fac, MidpointRounding.AwayFromZero)) / fac;
}
}
}
return(c);
}
protected override void ProcessInputObject(double value)
{
WriteObject(Special.Factorial(value));
}
/// <summary>
/// Gets the probability mass function (pmf) for
/// this distribution evaluated at point <c>x</c>.
/// </summary>
///
/// <param name="x">
/// A single point in the distribution range.</param>
///
/// <remarks>
/// The Probability Mass Function (PMF) describes the
/// probability that a given value <c>x</c> will occur.
/// </remarks>
///
/// <returns>
/// The probability of <c>x</c> occurring
/// in the current distribution.</returns>
///
public override double ProbabilityMassFunction(int x)
{
return((System.Math.Pow(lambda, x) / Special.Factorial(x)) * epml);
}
/// <summary>
/// Gets the cumulative distribution function (cdf) for
/// this distribution evaluated at point <c>k</c>.
/// </summary>
///
/// <param name="k">
/// 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(int k)
{
return(Gamma.LowerIncomplete(k + 1, lambda) / Special.Factorial(k));
}
/// <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(int x)
{
return(Special.Igam(x + 1, lambda) / Special.Factorial(x));
}
/// <summary>
/// Returns the value of the probability density function.
/// </summary>
/// <param name="x">Value</param>
/// <returns>float precision floating point number</returns>
public float Function(float x)
{
if (x < 0)
{
return(float.NaN);
}
return((float)Math.Pow(lambda, k) * (float)Math.Pow(x, k - 1) * (float)Math.Exp(-lambda * x) / Special.Factorial(k - 1));
}
/// <summary>
/// Computes the Complementary Cumulative Distribution Function (1-CDF)
/// for the Kolmogorov-Smirnov statistic's distribution.
/// </summary>
///
/// <param name="n">The sample size.</param>
/// <param name="x">The Kolmogorov-Smirnov statistic.</param>
/// <returns>Returns the complementary cumulative probability of the statistic
/// <paramref name="x"/> under a sample size <paramref name="n"/>.</returns>
///
public static double ComplementaryDistributionFunction(double n, double x)
{
double nxx = n * x * x; // nx²
// First of all, check if the given values do not represent
// a special case. There are some combination of values for
// which the distribution has a known, exact solution.
// Ruben-Gambino's Complement
if (x >= 1.0 || nxx >= 370.0)
{
return(0.0);
}
if (x <= 0.5 / n || nxx <= 0.0274)
{
return(1.0);
}
if (n == 1)
{
return(2.0 - 2.0 * x);
}
if (x <= 1.0 / n)
{
return((n <= 20) ? 1.0 - Special.Factorial(n) * Math.Pow(2.0 * x - 1.0 / n, n)
: 1.0 - Math.Exp(Special.LogFactorial(n) + n * Math.Log(2.0 * x - 1.0 / n)));
}
if (x >= 1.0 - 1.0 / n)
{
return(2.0 * Math.Pow(1.0 - x, n));
}
// This is not a special case. Continue processing to
// select the most adequate method for the given inputs
if (n <= 140)
{
// This is the first region (i) of the complementary
// CDF as detailed in Simard's paper. It is further
// divided into two sub-regions.
if (nxx >= 4.0)
{
// For x close to one, Simard's advocates the use of the one-
// sided Kolmogorov-Smirnov statistic as given by Miller (1956).
return(2 * OneSideUpperTail(n, x));
}
else
{
// For higher values of x, the direct cumulative
// distribution will be giving enough precision.
return(1.0 - CumulativeFunction(n, x));
}
}
else
{
// This is the second region (ii) of the complementary
// CDF discussed in Simard's paper. It is again divided
// into two sub-regions depending on the value of nx².
if (nxx >= 2.2)
{
// In this region, the Miller approximation returns
// at least 6 digits of precision (Simard, 2010).
return(2 * OneSideUpperTail(n, x));
}
else
{
// In this region, the direct cumulative
// distribution will give enough precision.
return(1.0 - CumulativeFunction(n, x));
}
}
}
/// <summary>
/// Computes the Cumulative Distribution Function (CDF)
/// for the Kolmogorov-Smirnov statistic's distribution.
/// </summary>
///
/// <param name="n">The sample size.</param>
/// <param name="x">The Kolmogorov-Smirnov statistic.</param>
/// <returns>Returns the cumulative probability of the statistic
/// <paramref name="x"/> under a sample size <paramref name="n"/>.</returns>
///
/// <remarks>
/// <para>
/// This function computes the cumulative probability P[Dn <= x] of
/// the Kolmogorov-Smirnov distribution using multiple methods as
/// suggested by Richard Simard (2010).</para>
///
/// <para>
/// Simard partitioned the problem of evaluating the CDF using multiple
/// approximation and asymptotic methods in order to achieve a best compromise
/// between speed and precision. This function follows the same partitioning as
/// Simard, which is described in the table below.</para>
///
/// <list type="table">
/// <listheader><term>For n <= 140 and:</term></listheader>
/// <item><term>1/n > x >= 1-1/n</term><description>Uses the Ruben-Gambino formula.</description></item>
/// <item><term>1/n < nx² < 0.754693</term><description>Uses the Durbin matrix algorithm.</description></item>
/// <item><term>0.754693 <= nx² < 4</term><description>Uses the Pomeranz algorithm.</description></item>
/// <item><term>4 <= nx² < 18</term><description>Uses the complementary distribution function.</description></item>
/// <item><term>nx² >= 18</term><description>Returns the constant 1.</description></item></list>
///
/// <list type="table">
/// <listheader><term>For 140 < n <= 10^5</term></listheader>
/// <item><term>nx² >= 18</term><description>Returns the constant 1.</description></item>
/// <item><term>nx^(3/2) < 1.4</term><description>Durbin matrix algorithm.</description></item>
/// <item><term>nx^(3/2) > 1.4</term><description>Pelz-Good asymptotic series.</description></item></list>
///
/// <list type="table">
/// <listheader><term>For n > 10^5</term></listheader>
/// <item><term>nx² >= 18</term><description>Returns the constant 1.</description></item>
/// <item><term>nx² < 18</term><description>Pelz-Good asymptotic series.</description></item></list>
///
/// </remarks>
///
public static double CumulativeFunction(double n, double x)
{
if (Double.IsNaN(x))
{
throw new ArgumentOutOfRangeException("x");
}
double nxx = n * x * x; // nx²
int nn = (int)Math.Ceiling(n);
// First of all, check if the given values do not represent
// a special case. There are some combination of values for
// which the distribution has a known, exact solution.
// Ruben-Gambino
if (x >= 1.0 || nxx >= 18.0)
{
return(1.0);
}
if (x <= 0.5 / n)
{
return(0.0);
}
if (n == 1)
{
return(2.0 * x - 1.0);
}
if (x <= 1.0 / n)
{
return((n <= 20) ? Special.Factorial(n) * Math.Pow(2.0 * x - 1.0 / n, n)
: Math.Exp(Special.LogFactorial(n) + n * Math.Log(2.0 * x - 1.0 / n)));
}
if (x >= 1.0 - 1.0 / n)
{
return(1.0 - 2.0 * Math.Pow(1.0 - x, n));
}
// This is not a special case. Continue processing to
// select the most adequate method for the given inputs
if (n <= 140)
{
// This is the first case (i) as referred in Simard's
// paper. Use exact algorithms depending on nx² with
// at least 13 to 15 decimal digits of precision.
// Durbin
if (nxx < 0.754693)
{
return(Durbin(nn, x));
}
// Pomeranz
if (nxx < 4.0)
{
return(Pomeranz(nn, x));
}
// Complementary CDF
return(1.0 - ComplementaryDistributionFunction(n, x));
}
else
{
if (n <= 100000)
{
// This is the second case (ii) referred in Simard's
// paper. Use either the Durbin approximation or the
// Pelz-Good asymptotic series depending on nx^(3/2).
// Obs:
//
// x^(3/2) = x^(1 + 1/2) = x*x^(1/2) = x*sqrt(x)
//
// (n*x) * sqrt(x) <= 1.40
// sqrt((n*x)*(n*x)) * sqrt(x) <= 1.40
// sqrt((n*x)*(n*x) * x) <= 1.40
// (n*x)*(n*x) * x <= 1.96
//
// n*n*x*x*x <= 1.96
//
if (n * nxx * x <= 1.96)
{
return(Durbin(nn, x));
}
else
{
return(PelzGood(n, x));
}
}
else
{
// This is the third case (iii) as referred in Simard's
// paper. Use only the Pelz-Good asymptotic series.
return(PelzGood(n, x));
}
}
}
/// <summary>
/// Gets the probability mass function (pmf) for
/// this distribution evaluated at point <c>x</c>.
/// </summary>
///
/// <param name="k">
/// A single point in the distribution range.</param>
///
/// <remarks>
/// The Probability Mass Function (PMF) describes the
/// probability that a given value <c>k</c> will occur.
/// </remarks>
///
/// <returns>
/// The probability of <c>x</c> occurring
/// in the current distribution.</returns>
///
protected internal override double InnerProbabilityMassFunction(int k)
{
return((Math.Pow(lambda, k) / Special.Factorial(k)) * epml);
}