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The first attempt towards a fix for #730.

pull/735/head
Jakub Bialogrodzki 6 years ago
parent
ad05896d3b
commit
5b6115131a
2 changed files with 179 additions and 6 deletions
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  1. 88
      src/Numerics.Tests/PolynomialTests.cs
  2. 97
      src/Numerics/Polynomial.cs

88
src/Numerics.Tests/PolynomialTests.cs
View File

@ -44,6 +44,7 @@ namespace MathNet.Numerics.UnitTests
[TestFixture, Category("Calculus")]
public class PolynomialTests
{
[TestCase(new double[] { 5, 4, 3, 0, 2 }, "5 + 4x + 3x^2 + 2x^4")]
[TestCase(new double[0], "0")]
[TestCase(new double[] { 0, 4, 3, 0, 0 }, "4x + 3x^2")]
@ -199,6 +200,33 @@ namespace MathNet.Numerics.UnitTests
}
}
// 2020-10-07 jbialogrodzki #730 This test focuses particularly on the issue at hand,
// i.e. multiplication of zero polynomials, but also attempts to provide more thorough UT
// for multiplication in general.
[TestCase(new double[] { }, new double[] { }, new double[] { })]
[TestCase(new double[] { 0 }, new double[] { }, new double[] { })]
[TestCase(new double[] { 1 }, new double[] { }, new double[] { })]
[TestCase(new double[] { 1, 2, 3 }, new double[] { }, new double[] { })]
[TestCase(new double[] { 0 }, new double[] { 0 }, new double[] { })]
[TestCase(new double[] { 1 }, new double[] { 0 }, new double[] { })]
[TestCase(new double[] { 1, 2, 3 }, new double[] { 0 }, new double[] { })]
[TestCase(new double[] { 2 }, new double[] { 3 }, new double[] { 6 })]
[TestCase(new double[] { 2, 3 }, new double[] { 4 }, new double[] { 8, 12 })]
[TestCase(new double[] { 2, 3 }, new double[] { 4, 5 }, new double[] { 8, 22, 15 })]
public void MultiplyTest2(double[] cLeft, double[] cRight, double[] cExpected)
{
var left = new Polynomial(cLeft);
var right = new Polynomial(cRight);
var expected = new Polynomial(cExpected);
var actualLR = left * right;
PolynomialTests.TestEqual(actualLR, expected);
var actualRL = right * left;
PolynomialTests.TestEqual(actualRL, expected);
}
[TestCase(new double[] { 5, 4, 0 }, "5 + 4x")]
[TestCase(new double[] { 0, 0, 0 }, "0")]
@ -382,5 +410,65 @@ namespace MathNet.Numerics.UnitTests
Assert.AreEqual(p_tar.Coefficients[k], p_res.Coefficients[k], msg);
}
}
// 2020-10-07 jbialogrodzki #730 This test focuses particularly on the issue at hand,
// i.e. evaluating zero polynomials, but also attempts to provide some UT for evaluation
// in general (as there has been none). Note the Complex API is tested with real values only.
[TestCase(new double[] { }, 0, 0)]
[TestCase(new double[] { }, 123, 0)]
[TestCase(new double[] { 0 }, 0, 0)]
[TestCase(new double[] { 0 }, 123, 0)]
[TestCase(new double[] { 1 }, 0, 1)]
[TestCase(new double[] { 1 }, 123, 1)]
[TestCase(new double[] { 2 }, 0, 2)]
[TestCase(new double[] { 2 }, 123, 2)]
[TestCase(new double[] { 1, 2 }, 0, 1)]
[TestCase(new double[] { 1, 2 }, 3, 7)]
[TestCase(new double[] { 1, 2, 3 }, 0, 1)]
[TestCase(new double[] { 1, 2, 3 }, 4, 57)]
public void EvaluateTest(double[] c, double z, double expected)
{
Complex DoubleToComplex(double value) => new Complex(value, 0);
var cComplex = c.Select(DoubleToComplex).ToArray();
var zComplex = DoubleToComplex(z);
var expectedComplex = DoubleToComplex(expected);
var p = new Polynomial(c);
// static double Evaluate(double, double[])
{
var actual = Polynomial.Evaluate(z, c);
Assert.AreEqual(expected, actual);
}
// static Complex Evaluate(Complex, double[])
{
var actual = Polynomial.Evaluate(zComplex, c);
Assert.AreEqual(expectedComplex, actual);
}
// static Complex Evaluate(Complex, Complex[])
{
var actual = Polynomial.Evaluate(zComplex, cComplex);
Assert.AreEqual(expectedComplex, actual);
}
// double Evaluate(double)
{
var actual = p.Evaluate(z);
Assert.AreEqual(expected, actual);
}
// Complex Evaluate(Complex)
{
var actual = p.Evaluate(zComplex);
Assert.AreEqual(expectedComplex, actual);
}
}
}
}

97
src/Numerics/Polynomial.cs
View File

@ -144,16 +144,36 @@ namespace MathNet.Numerics
/// </summary>
/// <param name="z">The location where to evaluate the polynomial at.</param>
/// <param name="coefficients">The coefficients of the polynomial, coefficient for power k at index k.</param>
/// <exception cref="ArgumentNullException">
/// <paramref name="coefficients"/> is a null reference.
/// </exception>
public static double Evaluate(double z, params double[] coefficients)
{
double sum = coefficients[coefficients.Length - 1];
for (int i = coefficients.Length - 2; i >= 0; --i)
// 2020-10-07 jbialogrodzki #730 Since this is public API we should probably
// handle null arguments? It doesn't seem to have been done consistently in this class though.
if (coefficients == null)
{
throw new ArgumentNullException(nameof(coefficients));
}
// 2020-10-07 jbialogrodzki #730 Zero polynomials need explicit handling.
// Without this check, we attempted to peek coefficients at negative indices!
int n = coefficients.Length;
if (n == 0)
{
return 0;
}
double sum = coefficients[n - 1];
for (int i = n - 2; i >= 0; --i)
{
sum *= z;
sum += coefficients[i];
}
return sum;
}
/// <summary>
@ -163,16 +183,36 @@ namespace MathNet.Numerics
/// </summary>
/// <param name="z">The location where to evaluate the polynomial at.</param>
/// <param name="coefficients">The coefficients of the polynomial, coefficient for power k at index k.</param>
/// <exception cref="ArgumentNullException">
/// <paramref name="coefficients"/> is a null reference.
/// </exception>
public static Complex Evaluate(Complex z, params double[] coefficients)
{
Complex sum = coefficients[coefficients.Length - 1];
for (int i = coefficients.Length - 2; i >= 0; --i)
// 2020-10-07 jbialogrodzki #730 Since this is a public API we should probably
// handle null arguments? It doesn't seem to have been done consistently in this class though.
if (coefficients == null)
{
throw new ArgumentNullException(nameof(coefficients));
}
// 2020-10-07 jbialogrodzki #730 Zero polynomials need explicit handling.
// Without this check, we attempted to peek coefficients at negative indices!
int n = coefficients.Length;
if (n == 0)
{
return 0;
}
Complex sum = coefficients[n - 1];
for (int i = n - 2; i >= 0; --i)
{
sum *= z;
sum += coefficients[i];
}
return sum;
}
/// <summary>
@ -182,16 +222,36 @@ namespace MathNet.Numerics
/// </summary>
/// <param name="z">The location where to evaluate the polynomial at.</param>
/// <param name="coefficients">The coefficients of the polynomial, coefficient for power k at index k.</param>
/// <exception cref="ArgumentNullException">
/// <paramref name="coefficients"/> is a null reference.
/// </exception>
public static Complex Evaluate(Complex z, params Complex[] coefficients)
{
Complex sum = coefficients[coefficients.Length - 1];
for (int i = coefficients.Length - 2; i >= 0; --i)
// 2020-10-07 jbialogrodzki #730 Since this is a public API we should probably
// handle null arguments? It doesn't seem to have been done consistently in this class though.
if (coefficients == null)
{
throw new ArgumentNullException(nameof(coefficients));
}
// 2020-10-07 jbialogrodzki #730 Zero polynomials need explicit handling.
// Without this check, we attempted to peek coefficients at negative indices!
int n = coefficients.Length;
if (n == 0)
{
return 0;
}
Complex sum = coefficients[n - 1];
for (int i = n - 2; i >= 0; --i)
{
sum *= z;
sum += coefficients[i];
}
return sum;
}
/// <summary>
@ -480,10 +540,34 @@ namespace MathNet.Numerics
/// <param name="a">Left polynomial</param>
/// <param name="b">Right polynomial</param>
/// <returns>Resulting Polynomial</returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="a"/> or <paramref name="b"/> is a null reference.
/// </exception>
public static Polynomial Multiply(Polynomial a, Polynomial b)
{
// 2020-10-07 jbialogrodzki #730 Since this is a public API we should probably
// handle null arguments? It doesn't seem to have been done consistently in this class though.
if (a == null)
{
throw new ArgumentNullException(nameof(a));
}
if (b == null)
{
throw new ArgumentNullException(nameof(b));
}
var ad = a.Degree;
var bd = b.Degree;
// 2020-10-07 jbialogrodzki #730 Zero polynomials need explicit handling.
// Without this check, we attempted to create arrays of negative lengths!
if (ad < 0 || bd < 0)
{
return Polynomial.Zero;
}
double[] ac = a.Coefficients;
double[] bc = b.Coefficients;
@ -499,6 +583,7 @@ namespace MathNet.Numerics
}
return new Polynomial(result);
}
/// <summary>

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