Math.NET Numerics
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// <copyright file="NormalTests.cs" company="Math.NET">
// Math.NET Numerics, part of the Math.NET Project
// http://numerics.mathdotnet.com
// http://github.com/mathnet/mathnet-numerics
// http://mathnetnumerics.codeplex.com
// Copyright (c) 2009-2010 Math.NET
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
// </copyright>
using System;
using System.Linq;
using MathNet.Numerics.Distributions;
using NUnit.Framework;
namespace MathNet.Numerics.UnitTests.DistributionTests.Continuous
{
using Random = System.Random;
/// <summary>
/// Normal distribution tests.
/// </summary>
[TestFixture]
public class NormalTests
{
/// <summary>
/// Set-up parameters.
/// </summary>
[SetUp]
public void SetUp()
{
Control.CheckDistributionParameters = true;
}
/// <summary>
/// Can create standard normal.
/// </summary>
[Test]
public void CanCreateStandardNormal()
{
var n = new Normal();
Assert.AreEqual(0.0, n.Mean);
Assert.AreEqual(1.0, n.StdDev);
}
/// <summary>
/// Can create normal.
/// </summary>
/// <param name="mean">Mean value.</param>
/// <param name="sdev">Standard deviation value.</param>
[TestCase(0.0, 0.0)]
[TestCase(10.0, 0.1)]
[TestCase(-5.0, 1.0)]
[TestCase(0.0, 10.0)]
[TestCase(10.0, 100.0)]
[TestCase(-5.0, Double.PositiveInfinity)]
public void CanCreateNormal(double mean, double sdev)
{
var n = new Normal(mean, sdev);
Assert.AreEqual(mean, n.Mean);
Assert.AreEqual(sdev, n.StdDev);
}
/// <summary>
/// Normal create fails with bad parameters.
/// </summary>
/// <param name="mean">Mean value.</param>
/// <param name="sdev">Standard deviation value.</param>
[TestCase(Double.NaN, 1.0)]
[TestCase(1.0, Double.NaN)]
[TestCase(Double.NaN, Double.NaN)]
[TestCase(1.0, -1.0)]
public void NormalCreateFailsWithBadParameters(double mean, double sdev)
{
Assert.Throws<ArgumentOutOfRangeException>(() => new Normal(mean, sdev));
}
/// <summary>
/// Can create normal from mean and standard deviation.
/// </summary>
/// <param name="mean">Mean value.</param>
/// <param name="sdev">Standard deviation value.</param>
[TestCase(0.0, 0.0)]
[TestCase(10.0, 0.1)]
[TestCase(-5.0, 1.0)]
[TestCase(0.0, 10.0)]
[TestCase(10.0, 100.0)]
[TestCase(-5.0, Double.PositiveInfinity)]
public void CanCreateNormalFromMeanAndStdDev(double mean, double sdev)
{
var n = Normal.WithMeanStdDev(mean, sdev);
Assert.AreEqual(mean, n.Mean);
Assert.AreEqual(sdev, n.StdDev);
}
/// <summary>
/// Can create normal from mean and variance.
/// </summary>
/// <param name="mean">Mean value.</param>
/// <param name="var">Variance value.</param>
[TestCase(0.0, 0.0)]
[TestCase(10.0, 0.1)]
[TestCase(-5.0, 1.0)]
[TestCase(0.0, 10.0)]
[TestCase(10.0, 100.0)]
[TestCase(-5.0, Double.PositiveInfinity)]
public void CanCreateNormalFromMeanAndVariance(double mean, double var)
{
var n = Normal.WithMeanVariance(mean, var);
AssertHelpers.AlmostEqualRelative(mean, n.Mean, 15);
AssertHelpers.AlmostEqualRelative(var, n.Variance, 15);
}
/// <summary>
/// Can create normal from mean and precision.
/// </summary>
/// <param name="mean">Mean value.</param>
/// <param name="prec">Precision value.</param>
[TestCase(0.0, 0.0)]
[TestCase(10.0, 0.1)]
[TestCase(-5.0, 1.0)]
[TestCase(0.0, 10.0)]
[TestCase(10.0, 100.0)]
[TestCase(-5.0, Double.PositiveInfinity)]
public void CanCreateNormalFromMeanAndPrecision(double mean, double prec)
{
var n = Normal.WithMeanPrecision(mean, prec);
AssertHelpers.AlmostEqualRelative(mean, n.Mean, 15);
AssertHelpers.AlmostEqualRelative(prec, n.Precision, 15);
}
/// <summary>
/// Validate ToString.
/// </summary>
[Test]
public void ValidateToString()
{
var n = new Normal(1d, 2d);
Assert.AreEqual("Normal(μ = 1, σ = 2)", n.ToString());
}
/// <summary>
/// Can set precision.
/// </summary>
/// <param name="prec">Precision value.</param>
[TestCase(-0.0)]
[TestCase(0.0)]
[TestCase(0.1)]
[TestCase(1.0)]
[TestCase(10.0)]
[TestCase(Double.PositiveInfinity)]
public void CanSetPrecision(double prec)
{
new Normal
{
Precision = prec
};
}
/// <summary>
/// Set precision fails with negative value.
/// </summary>
[Test]
public void SetPrecisionFailsWithNegativePrecision()
{
var n = new Normal();
Assert.Throws<ArgumentOutOfRangeException>(() => n.Precision = -1.0);
}
/// <summary>
/// Can set variance.
/// </summary>
/// <param name="var">Variance value.</param>
[TestCase(-0.0)]
[TestCase(0.0)]
[TestCase(0.1)]
[TestCase(1.0)]
[TestCase(10.0)]
[TestCase(Double.PositiveInfinity)]
public void CanSetVariance(double var)
{
var dist = new Normal
{
Variance = var
};
Assert.AreEqual(var, dist.Variance, 1e-14);
}
/// <summary>
/// Set variance fails with negative value.
/// </summary>
[Test]
public void SetVarianceFailsWithNegativeVariance()
{
var n = new Normal();
Assert.Throws<ArgumentOutOfRangeException>(() => n.Variance = -1.0);
}
/// <summary>
/// Can set standard deviation.
/// </summary>
/// <param name="sdev">Standard deviation value.</param>
[TestCase(-0.0)]
[TestCase(0.0)]
[TestCase(0.1)]
[TestCase(1.0)]
[TestCase(10.0)]
[TestCase(Double.PositiveInfinity)]
public void CanSetStdDev(double sdev)
{
var dist = new Normal
{
StdDev = sdev
};
Assert.AreEqual(sdev, dist.StdDev, 1e-14);
}
/// <summary>
/// Set standard deviation fails with negative value.
/// </summary>
[Test]
public void SetStdDevFailsWithNegativeStdDev()
{
var n = new Normal();
Assert.Throws<ArgumentOutOfRangeException>(() => n.StdDev = -1.0);
}
/// <summary>
/// Can set mean.
/// </summary>
/// <param name="mean">Mean value.</param>
[TestCase(Double.NegativeInfinity)]
[TestCase(-0.0)]
[TestCase(0.0)]
[TestCase(0.1)]
[TestCase(1.0)]
[TestCase(10.0)]
[TestCase(Double.PositiveInfinity)]
public void CanSetMean(double mean)
{
new Normal
{
Mean = mean
};
}
/// <summary>
/// Validate entropy.
/// </summary>
/// <param name="sdev">Standard deviation value.</param>
[TestCase(-0.0)]
[TestCase(0.0)]
[TestCase(0.1)]
[TestCase(1.0)]
[TestCase(10.0)]
[TestCase(Double.PositiveInfinity)]
public void ValidateEntropy(double sdev)
{
var n = new Normal(1.0, sdev);
Assert.AreEqual(Constants.LogSqrt2PiE + Math.Log(n.StdDev), n.Entropy);
}
/// <summary>
/// Validate skewness.
/// </summary>
/// <param name="sdev">Standard deviation value.</param>
[TestCase(-0.0)]
[TestCase(0.0)]
[TestCase(0.1)]
[TestCase(1.0)]
[TestCase(10.0)]
[TestCase(Double.PositiveInfinity)]
public void ValidateSkewness(double sdev)
{
var n = new Normal(1.0, sdev);
Assert.AreEqual(0.0, n.Skewness);
}
/// <summary>
/// Validate mean.
/// </summary>
/// <param name="mean">Mean value.</param>
[TestCase(Double.NegativeInfinity)]
[TestCase(-0.0)]
[TestCase(0.0)]
[TestCase(0.1)]
[TestCase(1.0)]
[TestCase(10.0)]
[TestCase(Double.PositiveInfinity)]
public void ValidateMode(double mean)
{
var n = new Normal(mean, 1.0);
Assert.AreEqual(mean, n.Mode);
}
/// <summary>
/// Validate median.
/// </summary>
/// <param name="mean">Mean value.</param>
[TestCase(Double.NegativeInfinity)]
[TestCase(-0.0)]
[TestCase(0.0)]
[TestCase(0.1)]
[TestCase(1.0)]
[TestCase(10.0)]
[TestCase(Double.PositiveInfinity)]
public void ValidateMedian(double mean)
{
var n = new Normal(mean, 1.0);
Assert.AreEqual(mean, n.Median);
}
/// <summary>
/// Validate minimum.
/// </summary>
[Test]
public void ValidateMinimum()
{
var n = new Normal();
Assert.AreEqual(Double.NegativeInfinity, n.Minimum);
}
/// <summary>
/// Validate maximum.
/// </summary>
[Test]
public void ValidateMaximum()
{
var n = new Normal();
Assert.AreEqual(Double.PositiveInfinity, n.Maximum);
}
/// <summary>
/// Validate density.
/// </summary>
/// <param name="mean">Mean value.</param>
/// <param name="sdev">Standard deviation value.</param>
[TestCase(0.0, 0.0)]
[TestCase(10.0, 0.1)]
[TestCase(-5.0, 1.0)]
[TestCase(0.0, 10.0)]
[TestCase(10.0, 100.0)]
[TestCase(-5.0, Double.PositiveInfinity)]
public void ValidateDensity(double mean, double sdev)
{
var n = Normal.WithMeanStdDev(mean, sdev);
for (var i = 0; i < 11; i++)
{
var x = i - 5.0;
var d = (mean - x) / sdev;
var pdf = Math.Exp(-0.5 * d * d) / (sdev * Constants.Sqrt2Pi);
Assert.AreEqual(pdf, n.Density(x));
Assert.AreEqual(pdf, Normal.PDF(mean, sdev, x));
}
}
/// <summary>
/// Validate density log.
/// </summary>
/// <param name="mean">Mean value.</param>
/// <param name="sdev">Standard deviation value.</param>
[TestCase(0.0, 0.0)]
[TestCase(10.0, 0.1)]
[TestCase(-5.0, 1.0)]
[TestCase(0.0, 10.0)]
[TestCase(10.0, 100.0)]
[TestCase(-5.0, Double.PositiveInfinity)]
public void ValidateDensityLn(double mean, double sdev)
{
var n = Normal.WithMeanStdDev(mean, sdev);
for (var i = 0; i < 11; i++)
{
var x = i - 5.0;
var d = (mean - x) / sdev;
var pdfln = (-0.5 * (d * d)) - Math.Log(sdev) - Constants.LogSqrt2Pi;
Assert.AreEqual(pdfln, n.DensityLn(x));
Assert.AreEqual(pdfln, Normal.PDFLn(mean, sdev, x));
}
}
/// <summary>
/// Can sample static.
/// </summary>
[Test]
public void CanSampleStatic()
{
Normal.Sample(new Random(), 0.0, 1.0);
}
/// <summary>
/// Can sample sequence static.
/// </summary>
[Test]
public void CanSampleSequenceStatic()
{
var ied = Normal.Samples(new Random(), 0.0, 1.0);
ied.Take(5).ToArray();
}
/// <summary>
/// Fail sample static with bad parameters.
/// </summary>
[Test]
public void FailSampleStatic()
{
Assert.Throws<ArgumentOutOfRangeException>(() => { var d = Normal.Sample(new Random(), 0.0, -1.0); });
}
/// <summary>
/// Fail sample sequence static with bad parameters.
/// </summary>
[Test]
public void FailSampleSequenceStatic()
{
Assert.Throws<ArgumentOutOfRangeException>(() => { var ied = Normal.Samples(new Random(), 0.0, -1.0).First(); });
}
/// <summary>
/// Can sample.
/// </summary>
[Test]
public void CanSample()
{
var n = new Normal();
n.Sample();
}
/// <summary>
/// Can sample sequence.
/// </summary>
[Test]
public void CanSampleSequence()
{
var n = new Normal();
var ied = n.Samples();
ied.Take(5).ToArray();
}
/// <summary>
/// Validate cumulative distribution.
/// </summary>
/// <param name="x">Input X value.</param>
/// <param name="f">Expected value.</param>
[TestCase(Double.NegativeInfinity, 0.0)]
[TestCase(-5.0, 0.00000028665157187919391167375233287464535385442301361187883)]
[TestCase(-2.0, 0.0002326290790355250363499258867279847735487493358890356)]
[TestCase(-0.0, 0.0062096653257761351669781045741922211278977469230927036)]
[TestCase(0.0, 0.0062096653257761351669781045741922211278977469230927036)]
[TestCase(4.0, 0.30853753872598689636229538939166226011639782444542207)]
[TestCase(5.0, 0.5)]
[TestCase(6.0, 0.69146246127401310363770461060833773988360217555457859)]
[TestCase(10.0, 0.9937903346742238648330218954258077788721022530769078)]
[TestCase(Double.PositiveInfinity, 1.0)]
public void ValidateCumulativeDistribution(double x, double f)
{
var n = Normal.WithMeanStdDev(5.0, 2.0);
AssertHelpers.AlmostEqualRelative(f, n.CumulativeDistribution(x), 9);
AssertHelpers.AlmostEqualRelative(f, Normal.CDF(5.0, 2.0, x), 9);
}
/// <summary>
/// Validate inverse cumulative distribution.
/// </summary>
/// <param name="x">Input X value.</param>
/// <param name="f">Expected value.</param>
[TestCase(Double.NegativeInfinity, 0.0)]
[TestCase(-5.0, 0.00000028665157187919391167375233287464535385442301361187883)]
[TestCase(-2.0, 0.0002326290790355250363499258867279847735487493358890356)]
[TestCase(-0.0, 0.0062096653257761351669781045741922211278977469230927036)]
[TestCase(0.0, .0062096653257761351669781045741922211278977469230927036)]
[TestCase(4.0, .30853753872598689636229538939166226011639782444542207)]
[TestCase(5.0, .5)]
[TestCase(6.0, .69146246127401310363770461060833773988360217555457859)]
[TestCase(10.0, 0.9937903346742238648330218954258077788721022530769078)]
[TestCase(Double.PositiveInfinity, 1.0)]
public void ValidateInverseCumulativeDistribution(double x, double f)
{
var n = Normal.WithMeanStdDev(5.0, 2.0);
AssertHelpers.AlmostEqualRelative(x, n.InverseCumulativeDistribution(f), 14);
AssertHelpers.AlmostEqualRelative(x, Normal.InvCDF(5.0, 2.0, f), 14);
}
/// <summary>
/// Can estimate distribution parameters.
/// </summary>
[TestCase(0.0, 0.0)]
[TestCase(10.0, 0.1)]
[TestCase(-5.0, 1.0)]
[TestCase(0.0, 5.0)]
[TestCase(10.0, 50.0)]
public void CanEstimateParameters(double mean, double stddev)
{
var original = new Normal(mean, stddev, new Random(100));
var estimated = Normal.Estimate(original.Samples().Take(10000));
AssertHelpers.AlmostEqualRelative(mean, estimated.Mean, 1);
AssertHelpers.AlmostEqualRelative(stddev, estimated.StdDev, 1);
}
}
}