@stdlib/stats
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Standard library statistical functions.
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{{alias}}( x, k, λ )
Evaluates the natural logarithm of the probability density function (PDF)
for an Erlang distribution with shape parameter `k` and rate parameter `λ`
at a value `x`.
If provided `NaN` as any argument, the function returns `NaN`.
If not provided a nonnegative integer for `k`, the function returns `NaN`.
If provided a non-positive value for `λ`, the function returns `NaN`.
Parameters
----------
x: number
Input value.
k: number
Shape parameter.
λ: number
Rate parameter.
Returns
-------
out: number
Evaluated logPDF.
Examples
--------
> var y = {{alias}}( 0.1, 1, 1.0 )
~-0.1
> y = {{alias}}( 0.5, 2, 2.5 )
~-0.111
> y = {{alias}}( -1.0, 4, 2.0 )
-Infinity
> y = {{alias}}( NaN, 1, 1.0 )
NaN
> y = {{alias}}( 0.0, NaN, 1.0 )
NaN
> y = {{alias}}( 0.0, 1, NaN )
NaN
> y = {{alias}}( 2.0, -2, 0.5 )
NaN
> y = {{alias}}( 2.0, 0.5, 0.5 )
NaN
> y = {{alias}}( 2.0, 0.0, 2.0 )
-Infinity
> y = {{alias}}( 0.0, 0.0, 2.0 )
Infinity
> y = {{alias}}( 2.0, 1, 0.0 )
NaN
> y = {{alias}}( 2.0, 1, -1.0 )
NaN
{{alias}}.factory( k, λ )
Returns a function for evaluating the natural logarithm of the probability
density function (PDF) of an Erlang distribution with shape parameter `k`
and rate parameter `λ`.
Parameters
----------
k: number
Shape parameter.
λ: number
Rate parameter.
Returns
-------
logpdf: Function
Logarithm of probability density function (PDF).
Examples
--------
> var myLogPDF = {{alias}}.factory( 6.0, 7.0 );
> y = myLogPDF( 7.0 )
~-32.382
See Also
--------