/// <summary>
/// Generates a random observation from the
/// F-distribution with the given parameters.
/// </summary>
///
/// <param name="d1">The first degree of freedom.</param>
/// <param name="d2">The second degree of freedom.</param>
///
/// <returns>A random double value sampled from the specified F-distribution.</returns>
///
public static double Random(int d1, int d2)
{
double x = GammaDistribution.Random(shape: d1 / 2.0, scale: 2);
double y = GammaDistribution.Random(shape: d2 / 2.0, scale: 2);
return(x / y);
}
/// <summary>
/// Estimates a new Gamma distribution from a given set of observations.
/// </summary>
///
public static GammaDistribution Estimate(double[] observations, double[] weights)
{
var n = new GammaDistribution();
n.Fit(observations, weights, null);
return(n);
}
/// <summary>
/// Generates a random observation from the
/// Beta distribution with the given parameters.
/// </summary>
///
/// <param name="alpha">The shape parameter α (alpha).</param>
/// <param name="beta">The shape parameter β (beta).</param>
/// <param name="source">The random number generator to use as a source of randomness.
/// Default is to use <see cref="Accord.Math.Random.Generator.Random"/>.</param>
///
/// <returns>A random double value sampled from the specified Beta distribution.</returns>
///
public static double Random(double alpha, double beta, Random source)
{
double x = GammaDistribution.Random(alpha, 1, source);
double y = GammaDistribution.Random(beta, 1, source);
return(x / (x + y));
}
/// <summary>
/// Generates a random observation from the
/// Beta distribution with the given parameters.
/// </summary>
///
/// <param name="alpha">The shape parameter α (alpha).</param>
/// <param name="beta">The shape parameter β (beta).</param>
///
/// <returns>A random double value sampled from the specified Beta distribution.</returns>
///
public static double Random(double alpha, double beta)
{
var rand = Accord.Math.Random.Generator.Random;
double x = GammaDistribution.Random(alpha, 1);
double y = GammaDistribution.Random(beta, 1);
return(x / (x + y));
}
/// <summary>
/// Generates a random vector of observations from the
/// Nakagami distribution with the given parameters.
/// </summary>
///
/// <param name="shape">The shape parameter μ.</param>
/// <param name="spread">The spread parameter ω.</param>
/// <param name="samples">The number of samples to generate.</param>
///
/// <returns>An array of double values sampled from the specified Nakagami distribution.</returns>
///
public static double[] Random(double shape, double spread, int samples)
{
double[] g = GammaDistribution.Random(shape: shape, scale: spread / shape, samples: samples);
for (int i = 0; i < g.Length; i++)
{
g[i] = Math.Sqrt(g[i]);
}
return(g);
}
/// <summary>
/// Generates a random vector of observations from the
/// Nakagami distribution with the given parameters.
/// </summary>
///
/// <param name="shape">The shape parameter μ.</param>
/// <param name="spread">The spread parameter ω.</param>
/// <param name="samples">The number of samples to generate.</param>
/// <param name="result">The location where to store the samples.</param>
/// <param name="source">The random number generator to use as a source of randomness.
/// Default is to use <see cref="Accord.Math.Random.Generator.Random"/>.</param>
///
/// <returns>An array of double values sampled from the specified Nakagami distribution.</returns>
///
public static double[] Random(double shape, double spread, int samples, double[] result, Random source)
{
GammaDistribution.Random(shape, spread / shape, samples, result, source: source);
for (int i = 0; i < result.Length; i++)
{
result[i] = Math.Sqrt(result[i]);
}
return(result);
}
/// <summary>
/// Generates a random vector of observations from the
/// F-distribution with the given parameters.
/// </summary>
///
/// <param name="d1">The first degree of freedom.</param>
/// <param name="d2">The second degree of freedom.</param>
/// <param name="samples">The number of samples to generate.</param>
/// <param name="result">The location where to store the samples.</param>
/// <param name="source">The random number generator to use as a source of randomness.
/// Default is to use <see cref="Accord.Math.Random.Generator.Random"/>.</param>
///
/// <returns>An array of double values sampled from the specified F-distribution.</returns>
///
public static double[] Random(int d1, int d2, int samples, double[] result, Random source)
{
double[] x = GammaDistribution.Random(shape: d1 / 2.0, scale: 2, samples: samples, result: result, source: source);
double[] y = GammaDistribution.Random(shape: d2 / 2.0, scale: 2, samples: samples, source: source);
for (int i = 0; i < x.Length; i++)
{
x[i] /= y[i];
}
return(x);
}
/// <summary>
/// Generates a random vector of observations from the
/// Beta distribution with the given parameters.
/// </summary>
///
/// <param name="alpha">The shape parameter α (alpha).</param>
/// <param name="beta">The shape parameter β (beta).</param>
/// <param name="samples">The number of samples to generate.</param>
/// <param name="result">The location where to store the samples.</param>
/// <param name="source">The random number generator to use as a source of randomness.
/// Default is to use <see cref="Accord.Math.Random.Generator.Random"/>.</param>
///
/// <returns>An array of double values sampled from the specified Beta distribution.</returns>
///
public static double[] Random(double alpha, double beta, int samples, double[] result, Random source)
{
double[] x = GammaDistribution.Random(alpha, 1, samples, result, source);
double[] y = GammaDistribution.Random(beta, 1, samples, source);
for (int i = 0; i < x.Length; i++)
{
result[i] = x[i] / (x[i] + y[i]);
}
return(result);
}
/// <summary>
/// Estimates a new Gamma distribution from a given set of observations.
/// </summary>
///
public static GammaDistribution Estimate(double[] observations,
double[] weights = null, double tol = 1e-8, int iterations = 1000)
{
var n = new GammaDistribution();
n.Fit(observations, weights, new GammaOptions()
{
Tolerance = tol,
Iterations = iterations
});
return(n);
}
/// <summary>
/// Generates a random vector of observations from the
/// F-distribution with the given parameters.
/// </summary>
///
/// <param name="d1">The first degree of freedom.</param>
/// <param name="d2">The second degree of freedom.</param>
/// <param name="samples">The number of samples to generate.</param>
///
/// <returns>An array of double values sampled from the specified F-distribution.</returns>
///
public static double[] Random(int d1, int d2, int samples)
{
double[] x = GammaDistribution.Random(shape: d1 / 2.0, scale: 2, samples: samples);
double[] y = GammaDistribution.Random(shape: d2 / 2.0, scale: 2, samples: samples);
for (int i = 0; i < x.Length; i++)
{
x[i] = x[i] / y[i];
}
return(x);
}
/// <summary>
/// Generates a random vector of observations from the
/// Beta distribution with the given parameters.
/// </summary>
///
/// <param name="alpha">The shape parameter α (alpha).</param>
/// <param name="beta">The shape parameter β (beta).</param>
/// <param name="samples">The number of samples to generate.</param>
/// <param name="result">The location where to store the samples.</param>
///
/// <returns>An array of double values sampled from the specified Beta distribution.</returns>
///
public static double[] Random(double alpha, double beta, int samples, double[] result)
{
var rand = Accord.Math.Random.Generator.Random;
double[] x = GammaDistribution.Random(alpha, 1, samples, result);
double[] y = GammaDistribution.Random(beta, 1, samples);
for (int i = 0; i < x.Length; i++)
{
result[i] = x[i] / (x[i] + y[i]);
}
return(result);
}
/// <summary>
/// Generates a random observation from the
/// Nakagami distribution with the given parameters.
/// </summary>
///
/// <param name="shape">The shape parameter μ.</param>
/// <param name="spread">The spread parameter ω.</param>
/// <param name="source">The random number generator to use as a source of randomness.
/// Default is to use <see cref="Accord.Math.Random.Generator.Random"/>.</param>
///
/// <returns>A random double value sampled from the specified Nakagami distribution.</returns>
///
public static double Random(double shape, double spread, Random source)
{
return(Math.Sqrt(GammaDistribution.Random(shape: shape, scale: spread / shape, source: source)));
}
/// <summary>
/// Generates a random vector of observations from the
/// Chi-Square distribution with the given parameters.
/// </summary>
///
/// <returns>An array of double values sampled from the specified Chi-Square distribution.</returns>
///
public static double[] Random(int degreesOfFreedom, int samples, double[] result, Random source)
{
return(GammaDistribution.Random(shape: degreesOfFreedom / 2.0, scale: 2,
samples: samples, result: result, source: source));
}
/// <summary>
/// Generates a random vector of observations from the current distribution.
/// </summary>
///
/// <param name="samples">The number of samples to generate.</param>
/// <param name="result">The location where to store the samples.</param>
///
/// <returns>A random vector of observations drawn from this distribution.</returns>
///
public override double[] Generate(int samples, double[] result)
{
return(GammaDistribution.Random(shape: degreesOfFreedom / 2.0, scale: 2, samples: samples, result: result));
}
/// <summary>
/// Generates a random vector of observations from the current distribution.
/// </summary>
///
/// <param name="samples">The number of samples to generate.</param>
/// <returns>A random vector of observations drawn from this distribution.</returns>
///
public double[] Generate(int samples)
{
return(GammaDistribution.Random(shape: degreesOfFreedom / 2.0, scale: 2, samples: samples));
}
/// <summary>
/// Generates a random observation from the current distribution.
/// </summary>
///
/// <returns>A random observations drawn from this distribution.</returns>
///
public double Generate()
{
return(GammaDistribution.Random(shape: degreesOfFreedom / 2.0, scale: 2));
}
/// <summary>
/// Generates a random vector of observations from the
/// Chi-Square distribution with the given parameters.
/// </summary>
///
/// <returns>An array of double values sampled from the specified Chi-Square distribution.</returns>
///
public static double[] Random(int degreesOfFreedom, int samples)
{
return(GammaDistribution.Random(shape: degreesOfFreedom / 2.0, scale: 2, samples: samples));
}
/// <summary>
/// Generates a random observation from the
/// Nakagami distribution with the given parameters.
/// </summary>
///
/// <param name="shape">The shape parameter μ.</param>
/// <param name="spread">The spread parameter ω.</param>
///
/// <returns>A random double value sampled from the specified Nakagami distribution.</returns>
///
public static double Random(double shape, double spread)
{
double g = GammaDistribution.Random(shape: shape, scale: spread / shape);
return(Math.Sqrt(g));
}
/// <summary>
/// Generates a random observation from the
/// Chi-Square distribution with the given parameters.
/// </summary>
///
/// <param name="degreesOfFreedom">The degrees of freedom for the distribution.</param>
///
/// <returns>A random double value sampled from the specified Chi-Square distribution.</returns>
///
public static double Random(int degreesOfFreedom)
{
return(GammaDistribution.Random(shape: degreesOfFreedom / 2.0, scale: 2));
}
