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java.lang.Objectumontreal.iro.lecuyer.hups.PointSet
umontreal.iro.lecuyer.hups.HaltonSequence
public class HaltonSequence
This class implements the sequence of Halton, which is essentially a modification of Hammersley nets for producing an infinite sequence of points having low discrepancy. The ith point in s dimensions is
RadicalInverse
, and where
2 = b1 < ... < bs are the s smallest prime numbers in
increasing order.
A fast method is implemented to generate randomized Halton sequences, starting from an arbitrary points x0.
The points can be ``scrambled'' by applying a permutation to the
digits of i before computing each coordinate, in the same way as for the class
HammersleyPointSet
, for all coordinates j >= 0.
Constructor Summary | |
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HaltonSequence(int dim)
Constructs a new Halton sequence in dim dimensions. |
Method Summary | |
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void |
addFaurePermutations()
Permutes the digits using Faure permutations for all coordinates. |
void |
ErasePermutations()
Erases the Faure permutations: from now on, the digits will not be Faure permuted. |
double |
getCoordinate(int i,
int j)
Returns ui, j, the coordinate j of the point i. |
int |
getNumPoints()
Returns the number of points. |
void |
init(double[] x0)
Initializes the Halton sequence starting at point x0. |
Methods inherited from class umontreal.iro.lecuyer.hups.PointSet |
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addRandomShift, addRandomShift, addRandomShift, addRandomShift, clearRandomShift, formatPoints, formatPoints, getDimension, iterator, randomize, randomize, randomize, randomize, toString, unrandomize |
Methods inherited from class java.lang.Object |
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equals, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
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public HaltonSequence(int dim)
dim
- dimensionMethod Detail |
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public void init(double[] x0)
x0
- starting point of the Halton sequencepublic void addFaurePermutations()
public void ErasePermutations()
public int getNumPoints()
PointSet
getNumPoints
in class PointSet
public double getCoordinate(int i, int j)
PointSet
getCoordinate
in class PointSet
i
- index of the point to look forj
- index of the coordinate to look for
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