/// <summary>Initializes a new instance of the <see cref="HaltonSequence" /> class.</summary>
/// <param name="dimensionCount">The number of dimensions.</param>
/// <param name="startIndex">The start index.</param>
/// <exception cref="ArgumentException">Thrown when the specified index is negative.
/// or
/// The specified number of dimensions is less than 1.</exception>
public HaltonSequence(int dimensionCount, int startIndex)
{
if (dimensionCount < 1)
{
throw new ArgumentException("The number of dimensions must be greater than zero.", nameof(dimensionCount));
}
if (startIndex < 0)
{
throw new ArgumentException("The index must not be negative.", nameof(startIndex));
}
this.dimensionCount = dimensionCount;
vanDerCorputSequences = new VanDerCorputSequence[dimensionCount];
for (int j = 0; j < dimensionCount; j++)
{
vanDerCorputSequences[j] = new VanDerCorputSequence(startIndex, PrimeNumberMath.Primes[j + 1]);
}
}
/// <summary>Gets the original index of an element of the Halton sequence.</summary>
/// <param name="element">The element of the Halton sequence.</param>
/// <returns>The corresponding index.</returns>
/// <exception cref="OverflowException">Thrown when the resulting integer value is too large.</exception>
/// <exception cref="ArgumentNullException">Thrown when the specified element is <c>null</c>.</exception>
/// <exception cref="ArgumentException">Thrown when the specified element does not contain any values.
/// or
/// A component is less than 0 or greater than or equal to 1.</exception>
/// <remarks>Only the first component, assumed to be computed with base 2, is used for computing the index.</remarks>
public static int Invert(IReadOnlyList <double> element)
{
if (element == null)
{
throw new ArgumentNullException(nameof(element));
}
if (element.Count == 0)
{
throw new ArgumentException("The element is empty.", nameof(element));
}
if (element.Any(c => c < 0.0 || c >= 1.0))
{
throw new ArgumentException("Each component must be >= 0 and < 1.", nameof(element));
}
// Invert using the first component only, because working with base 2 is accurate.
return(VanDerCorputSequence.Invert(element[0]));
}
