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SSJ V. 2.6. |
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java.lang.Object umontreal.iro.lecuyer.rng.RandomStreamBase
public abstract class RandomStreamBase
This class provides a convenient foundation on which RNGs can be built. It implements all the methods which do not depend directly on the generator itself, but only on its output, which is to be defined by implementing the abstract method nextValue. In the present class, all methods returning random numbers directly or indirectly (nextDouble, nextArrayOfDouble, nextInt and nextArrayOfInt) call nextValue. Thus, to define a subclass that implements a RNG, it suffices to implement nextValue, in addition to the reset... and toString methods. Of course, the other methods may also be overridden for improved efficiency.
If the nextValue already generates numbers with a precision of
53-bits or higher, then nextDouble
can be overridden to improve
the performance. The mechanism for increasing the precision assumes that
nextValue returns at least 29 bits of precision, in which case
the higher precision numbers will have roughly 52 bits of precision.
This mechanism was designed primarily for RNGs that return numbers with
around 30 to 32 bits of precision.
RandomStreamBase
and its subclasses are implementing the Serializable
interface.
Each class has a serial number wich represent the class version.
For instance 70510 means that the last change was the 10th May 2007.
Constructor Summary | |
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RandomStreamBase()
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Method Summary | |
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RandomStreamBase |
clone()
Clones the current generator and return its copy. |
String |
formatState()
Deprecated. |
String |
formatStateFull()
Deprecated. |
void |
increasedPrecision(boolean incp)
After calling this method with incp = true, each call to the RNG (direct or indirect) for this stream will return a uniform random number with more bits of precision than what is returned by nextValue, and will advance the state of the stream by 2 steps instead of 1 (i.e., nextValue will be called twice for each random number). |
void |
nextArrayOfDouble(double[] u,
int start,
int n)
Calls nextDouble n times to fill the array u. |
void |
nextArrayOfInt(int i,
int j,
int[] u,
int start,
int n)
Calls nextInt n times to fill the array u. |
double |
nextDouble()
Returns a uniform random number between 0 and 1 from the stream. |
int |
nextInt(int i,
int j)
Calls nextDouble once to create one integer between i and j. |
abstract void |
resetNextSubstream()
Reinitializes the stream to the beginning of its next substream: Ng is computed, and Cg and Bg are set to Ng. |
abstract void |
resetStartStream()
Reinitializes the stream to its initial state Ig: Cg and Bg are set to Ig. |
abstract void |
resetStartSubstream()
Reinitializes the stream to the beginning of its current substream: Cg is set to Bg. |
abstract String |
toString()
Returns a string containing the current state of this stream. |
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 RandomStreamBase()
Method Detail |
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public abstract void resetStartStream()
RandomStream
resetStartStream
in interface RandomStream
public abstract void resetStartSubstream()
RandomStream
resetStartSubstream
in interface RandomStream
public abstract void resetNextSubstream()
RandomStream
resetNextSubstream
in interface RandomStream
public abstract String toString()
RandomStream
toString
in interface RandomStream
toString
in class Object
public void increasedPrecision(boolean incp)
More precisely, if s is a stream of a subclass of RandomStreamBase, when the precision has been increased, the instruction ``u = s.nextDouble()'', is equivalent to ``u = (s.nextValue() + s.nextValue()*fact) % 1.0'' where the constant fact is equal to 2-24. This also applies when calling nextDouble indirectly (e.g., via nextInt, etc.). By default, or if this method is called again with incp = false, each call to nextDouble for this stream advances the state by 1 step and returns the same number as nextValue.
incp
- if the generator will be set to high precision modepublic double nextDouble()
increasedPrecision
.
The generators programmed in SSJ never return the values 0 or 1.
nextDouble
in interface RandomStream
public void nextArrayOfDouble(double[] u, int start, int n)
nextArrayOfDouble
in interface RandomStream
u
- the array in which the numbers will be storedstart
- the first index of u to be usedn
- the number of random numbers to put in upublic int nextInt(int i, int j)
nextInt
in interface RandomStream
i
- the smallest possible returned integerj
- the largest possible returned integer
public void nextArrayOfInt(int i, int j, int[] u, int start, int n)
nextArrayOfInt
in interface RandomStream
i
- the smallest possible integer to put in uj
- the largest possible integer to put in uu
- the array in which the numbers will be storedstart
- the first index of u to be usedn
- the number of random numbers to put in u@Deprecated public String formatState()
@Deprecated public String formatStateFull()
public RandomStreamBase clone()
clone
in interface CloneableRandomStream
clone
in class Object
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SSJ V. 2.6. |
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