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public interface DiscreteDistribution
A DiscreteDistribution
provides a probability
distribution over long integer outcomes. Mathematically, such a
distribution defines a discretevalued random variable.
Discrete probability distributions return values between
0.0
and 1.0
inclusive for outcomes. The
sum of the probabilities over all integers should be
1.0
, but it may be less than 1.0
for the
sum of all integers representable as longs (64 bits). Discrete
distributions are also required to return log (base 2)
probabilities to support probabilities very close to 0.0 or 1.0.
Cumulative probabilities may be calculated over discrete distributions. A cumulative probabilty is a sum of probabilities within a given range.
Discrete distributions optionally implement methods to return their mean, variance and entropy. Discrete distributions are required to indicate the minimum and maximum outcome with nonzero probability. This allows cumulative probabilities, means, variances and entropies to be computed by iterating over values in range. If there are no minimum or maximum values, these methods should return the minimum and maximum long values respectively.
For more information, see:
Method Summary  

double 
cumulativeProbability(long lowerBound,
long upperBound)
Returns the probability that an outcome will fall in the range between the specified lower and upper bounds inclusive. 
double 
cumulativeProbabilityGreater(long lowerBound)
Returns the probability an outcome will be greater than or equal to the specified outcome. 
double 
cumulativeProbabilityLess(long upperBound)
Returns the probability an outcome will be less than or equal to the specified outcome. 
double 
entropy()
Returns the entropy of this distribution. 
double 
log2Probability(long outcome)
Returns the log (base 2) probability of the specified outcome. 
long 
maxOutcome()
Returns the maximum outcome with nonzero probability. 
double 
mean()
Returns the mean of this distribution. 
long 
minOutcome()
Returns the minimum outcome with nonzero probability. 
double 
probability(long outcome)
Returns the probability of the specified outcome. 
double 
variance()
Returns the variance of this distribution. 
Method Detail 

double probability(long outcome)
outcome
 The discrete outcome.
double log2Probability(long outcome)
outcome
 The discrete outcome.
double cumulativeProbabilityLess(long upperBound)
upperBound
 Upper bound of the outcome.
double cumulativeProbabilityGreater(long lowerBound)
lowerBound
 Lower bound of outcomes considered.
double cumulativeProbability(long lowerBound, long upperBound)
lowerBound
 Lower bound of outcomes considered.upperBound
 Upper bound of the outcome.
long minOutcome()
Long.MIN_VALUE
.
long maxOutcome()
Long.MAX_VALUE
.
double mean()
UnsupportedOperationException
 If this operation is not
supported.double variance()
UnsupportedOperationException
 If this operation is not
supported.double entropy()
UnsupportedOperationException
 If this operation is not
supported.


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