Stochastic Simulation in Java

This abstract class defines the basic methods for accessing and manipulating point sets. More...
Classes  
class  DefaultPointSetIterator 
Public Member Functions  
int  getDimension () 
Returns the dimension (number of available coordinates) of the point set. More...  
int  getNumPoints () 
Returns the number of points. More...  
abstract double  getCoordinate (int i, int j) 
Returns \(u_{i,j}\), the coordinate \(j\) of the point \(i\). More...  
PointSetIterator  iterator () 
Constructs and returns a point set iterator. More...  
void  setStream (RandomStream stream) 
Sets the random stream used to generate random shifts to stream . More...  
RandomStream  getStream () 
Returns the random stream used to generate random shifts. More...  
void  randomize (PointSetRandomization rand) 
Randomizes the point set using the given rand . More...  
void  addRandomShift (int d1, int d2, RandomStream stream) 
This method does nothing for this generic class. More...  
void  addRandomShift (RandomStream stream) 
This method does nothing for this generic class. More...  
void  addRandomShift (int d1, int d2) 
Similar to addRandomShift(d1, d2, stream) , with the current random stream.  
void  addRandomShift () 
Similar to addRandomShift(0, d2, stream) with the current random stream and d2 the dimension of the current random shift.  
void  clearRandomShift () 
Erases the current random shift, if any.  
void  randomize (int fromDim, int toDim, RandomStream stream) 
By default, this method simply calls addRandomShift (fromDim, toDim, stream) , which does nothing.  
void  randomize (RandomStream stream) 
By default, this method simply calls randomize(0, dim, stream).  
void  randomize (int d1, int d2) 
By default, this method simply calls addRandomShift(d1, d2) .  
void  randomize () 
By default, this method simply calls addRandomShift() .  
void  unrandomize () 
By default, this method simply calls clearRandomShift() .  
String  toString () 
Formats a string that contains information about the point set. More...  
String  formatPoints () 
Same as invoking formatPoints(n, d) with \(n\) and \(d\) equal to the number of points and the dimension of this object, respectively. More...  
String  formatPoints (int n, int d) 
Formats a string that displays the same information as returned by toString, together with the first \(d\) coordinates of the first \(n\) points. More...  
String  formatPoints (PointSetIterator iter) 
Same as invoking formatPoints(iter, n, d) with \(n\) and \(d\) equal to the number of points and the dimension, respectively. More...  
String  formatPoints (PointSetIterator iter, int n, int d) 
Same as invoking formatPoints(n, d), but prints the points by calling iter repeatedly. More...  
String  formatPointsBase (int b) 
Similar to formatPoints(), but the points coordinates are printed in base \(b\). More...  
String  formatPointsBase (int n, int d, int b) 
Similar to formatPoints(n, d), but the points coordinates are printed in base \(b\). More...  
String  formatPointsBase (PointSetIterator iter, int b) 
Similar to formatPoints(iter), but the points coordinates are printed in base \(b\). More...  
String  formatPointsBase (PointSetIterator iter, int n, int d, int b) 
Similar to formatPoints(iter, n, d), but the points coordinates are printed in base \(b\). More...  
String  formatPointsNumbered () 
Same as invoking formatPointsNumbered(n, d) with \(n\) and \(d\) equal to the number of points and the dimension, respectively. More...  
String  formatPointsNumbered (int n, int d) 
Same as invoking formatPoints(n,d), except that the points are numbered. More...  
Protected Attributes  
double  EpsilonHalf = 1.0 / Num.TWOEXP[55] 
int  dim = 0 
int  numPoints = 0 
int  dimShift = 0 
int  capacityShift = 0 
RandomStream  shiftStream 
Static Protected Attributes  
static final int  MAXBITS = 31 
This abstract class defines the basic methods for accessing and manipulating point sets.
A point set can be represented as a twodimensional array, whose element \((i,j)\) contains \(u_{i,j}\), the coordinate \(j\) of point \(i\). Each coordinate \(u_{i,j}\) is assumed to be in the unit interval \([0,1]\). Whether the values 0 and 1 can occur may depend on the actual implementation of the point set.
All points have the same number of coordinates (their dimension) and this number can be queried by getDimension. The number of points is queried by getNumPoints. The points and coordinates are both numbered starting from 0 and their number can actually be infinite.
The iterator method provides a point set iterator which permits one to enumerate the points and their coordinates. Several iterators over the same point set can coexist at any given time. These iterators are instances of a hidden innerclass that implements the PointSetIterator interface. The default implementation of iterator provided here relies on the method getCoordinate to access the coordinates directly. However, this approach is rarely efficient. Specialized implementations that dramatically improve the performance are provided in subclasses of PointSet. The PointSetIterator interface actually extends the umontreal.ssj.rng.RandomStream interface, so that the iterator can also be seen as a umontreal.ssj.rng.RandomStream and used wherever such a stream is required for generating uniform random numbers. This permits one to easily replace pseudorandom numbers by the coordinates of a selected set of highlyuniform points, i.e., to replace Monte Carlo by quasiMonte Carlo in a simulation program.
The class also offers tools to manipulate a list of randomizations that can be applied to this point set.
This abstract class has only one abstract method: getCoordinate. Providing an implementation for this method is already sufficient for the subclass to work. However, in many cases, efficiency can be dramatically improved by overwriting iterator to provide a custom iterator that does not necessarily rely on getCoordinate. In fact, direct use of getCoordinate to access the coordinates is generally discouraged. One should access the points and coordinates via the iterators.
The builtin range checks require some extra time and also assumes that nobody ever uses negative indices. If getCoordinate is not accessed directly by the user, it may be implemented without range checks.
addRandomShift
and clearRandomShift
methods, because they are too specialized and not appropriate for all kinds of point sets. We can also make the randomize(stream)
methods abstract, or make them do nothing by default.void addRandomShift  (  int  d1, 
int  d2,  
RandomStream  stream  
) 
This method does nothing for this generic class.
In some subclasses, it adds a random shift to all the points of the point set, using stream stream
to generate the random numbers, for coordinates d1
to d21
.
void addRandomShift  (  RandomStream  stream  ) 
This method does nothing for this generic class.
Similar to addRandomShift (0, d2, stream)
, with d2
the dimension of the current random shift.
String formatPoints  (  ) 
Same as invoking formatPoints(n, d) with \(n\) and \(d\) equal to the number of points and the dimension of this object, respectively.
UnsupportedOperationException  if the number of points or dimension of the point set is infinite 
String formatPoints  (  int  n, 
int  d  
) 
Formats a string that displays the same information as returned by toString, together with the first \(d\) coordinates of the first \(n\) points.
If \(n\) is larger than the number of points in the point set, it is reset to that number. If \(d\) is larger than the dimension of the points, it is reset to that dimension. The points are printed in the simplest format, separated by spaces, by calling the default iterator repeatedly.
n  number of points 
d  dimension 
String formatPoints  (  PointSetIterator  iter  ) 
Same as invoking formatPoints(iter, n, d) with \(n\) and \(d\) equal to the number of points and the dimension, respectively.
iter  iterator associated to the point set 
UnsupportedOperationException  if the number of points or dimension of the point set is infinite 
String formatPoints  (  PointSetIterator  iter, 
int  n,  
int  d  
) 
Same as invoking formatPoints(n, d), but prints the points by calling iter
repeatedly.
The order of the printed points may be different than the one resulting from the default iterator.
iter  iterator associated to the point set 
n  number of points 
d  dimension 
String formatPointsBase  (  int  b  ) 
Similar to formatPoints(), but the points coordinates are printed in base \(b\).
b  base 
UnsupportedOperationException  if the number of points or dimension of the point set is infinite 
String formatPointsBase  (  int  n, 
int  d,  
int  b  
) 
Similar to formatPoints(n, d), but the points coordinates are printed in base \(b\).
n  number of points 
d  dimension 
b  base 
String formatPointsBase  (  PointSetIterator  iter, 
int  b  
) 
Similar to formatPoints(iter), but the points coordinates are printed in base \(b\).
iter  iterator associated to the point set 
b  base 
UnsupportedOperationException  if the number of points or dimension of the point set is infinite 
String formatPointsBase  (  PointSetIterator  iter, 
int  n,  
int  d,  
int  b  
) 
Similar to formatPoints(iter, n, d), but the points coordinates are printed in base \(b\).
iter  iterator associated to the point set 
n  number of points 
d  dimension 
b  base 
String formatPointsNumbered  (  ) 
Same as invoking formatPointsNumbered(n, d) with \(n\) and \(d\) equal to the number of points and the dimension, respectively.
UnsupportedOperationException  if the number of points or dimension of the point set is infinite 
String formatPointsNumbered  (  int  n, 
int  d  
) 
Same as invoking formatPoints(n,d), except that the points are numbered.
n  number of points 
d  dimension 

abstract 
Returns \(u_{i,j}\), the coordinate \(j\) of the point \(i\).
getCoordinate
de certaines classes ne tient pas compte du random shift, contrairement à l’itérateur de la même classe. Fautil que toutes les getCoordinate
implémentent le random shift quand il existe? i  index of the point to look for 
j  index of the coordinate to look for 
int getDimension  (  ) 
Returns the dimension (number of available coordinates) of the point set.
If the dimension is actually infinite, Integer.MAX_VALUE
is returned.
Integer.MAX_VALUE
if it is infinite int getNumPoints  (  ) 
Returns the number of points.
If this number is actually infinite, Integer.MAX_VALUE
is returned.
Integer.MAX_VALUE
if the point set has an infinity of points. RandomStream getStream  (  ) 
Returns the random stream used to generate random shifts.
PointSetIterator iterator  (  ) 
Constructs and returns a point set iterator.
The default implementation returns an iterator that uses the method getCoordinate(i,j) to iterate over the points and coordinates, but subclasses can reimplement it for better efficiency.
void randomize  (  PointSetRandomization  rand  ) 
Randomizes the point set using the given rand
.
rand  PointSetRandomization to use 
void setStream  (  RandomStream  stream  ) 
Sets the random stream used to generate random shifts to stream
.
stream  the new random stream 
String toString  (  ) 
Formats a string that contains information about the point set.