Serializable
, RealDistribution
public class TDistribution extends AbstractRealDistribution
DEFAULT_SOLVER_ABSOLUTE_ACCURACY
Constructor | Description |
---|---|
TDistribution(double degreesOfFreedom) |
Create a t distribution using the given degrees of freedom.
|
TDistribution(double degreesOfFreedom,
double inverseCumAccuracy) |
Create a t distribution using the given degrees of freedom and the
specified inverse cumulative probability absolute accuracy.
|
Modifier and Type | Method | Description |
---|---|---|
double |
cumulativeProbability(double x) |
For a random variable
X whose values are distributed according
to this distribution, this method returns P(X <= x) . |
double |
density(double x) |
Returns the probability density function (PDF) of this distribution
evaluated at the specified point
x . |
double |
getDegreesOfFreedom() |
Access the degrees of freedom.
|
double |
getNumericalMean() |
Use this method to get the numerical value of the mean of this
distribution.
|
double |
getNumericalVariance() |
Use this method to get the numerical value of the variance of this
distribution.
|
double |
getSupportLowerBound() |
Access the lower bound of the support.
|
double |
getSupportUpperBound() |
Access the upper bound of the support.
|
boolean |
isSupportConnected() |
Use this method to get information about whether the support is connected,
i.e.
|
double |
logDensity(double x) |
Returns the natural logarithm of the probability density function
(PDF) of this distribution evaluated at the specified point
x . |
getSolverAbsoluteAccuracy, inverseCumulativeProbability, probability
public TDistribution(double degreesOfFreedom) throws MathIllegalArgumentException
degreesOfFreedom
- Degrees of freedom.MathIllegalArgumentException
- if degreesOfFreedom <= 0
public TDistribution(double degreesOfFreedom, double inverseCumAccuracy) throws MathIllegalArgumentException
degreesOfFreedom
- Degrees of freedom.inverseCumAccuracy
- the maximum absolute error in inverse
cumulative probability estimates
(defaults to AbstractRealDistribution.DEFAULT_SOLVER_ABSOLUTE_ACCURACY
).MathIllegalArgumentException
- if degreesOfFreedom <= 0
public double getDegreesOfFreedom()
public double density(double x)
x
. In general, the PDF is
the derivative of the CDF
.
If the derivative does not exist at x
, then an appropriate
replacement should be returned, e.g. Double.POSITIVE_INFINITY
,
Double.NaN
, or the limit inferior or limit superior of the
difference quotient.x
- the point at which the PDF is evaluatedx
public double logDensity(double x)
x
.
In general, the PDF is the derivative of the CDF
.
If the derivative does not exist at x
, then an appropriate replacement
should be returned, e.g. Double.POSITIVE_INFINITY
, Double.NaN
,
or the limit inferior or limit superior of the difference quotient. Note that
due to the floating point precision and under/overflow issues, this method will
for some distributions be more precise and faster than computing the logarithm of
RealDistribution.density(double)
.
The default implementation simply computes the logarithm of density(x)
.
logDensity
in interface RealDistribution
logDensity
in class AbstractRealDistribution
x
- the point at which the PDF is evaluatedx
public double cumulativeProbability(double x)
X
whose values are distributed according
to this distribution, this method returns P(X <= x)
. In other
words, this method represents the (cumulative) distribution function
(CDF) for this distribution.x
- the point at which the CDF is evaluatedx
public double getNumericalMean()
df
, the mean is
df > 1
then 0
,Double.NaN
).Double.NaN
if it is not definedpublic double getNumericalVariance()
df
, the variance is
df > 2
then df / (df - 2)
,1 < df <= 2
then positive infinity
(Double.POSITIVE_INFINITY
),Double.NaN
).Double.POSITIVE_INFINITY
as
for certain cases in TDistribution
)
or Double.NaN
if it is not definedpublic double getSupportLowerBound()
inverseCumulativeProbability(0)
. In other words, this
method must return
inf {x in R | P(X <= x) > 0}
.
Double.NEGATIVE_INFINITY
)public double getSupportUpperBound()
inverseCumulativeProbability(1)
. In other words, this
method must return
inf {x in R | P(X <= x) = 1}
.
Double.POSITIVE_INFINITY
)public boolean isSupportConnected()
true
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