@stdlib/stats
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Standard library statistical functions.
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{{alias}}( x, λ )
Evaluates the cumulative distribution function (CDF) for a Poisson
distribution with mean parameter `λ` at a value `x`.
If provided `NaN` as any argument, the function returns `NaN`.
If provided a negative value for `λ`, the function returns `NaN`.
Parameters
----------
x: number
Input value.
λ: number
Mean parameter.
Returns
-------
out: number
Evaluated CDF.
Examples
--------
> var y = {{alias}}( 2.0, 0.5 )
~0.986
> y = {{alias}}( 2.0, 10.0 )
~0.003
> y = {{alias}}( -1.0, 4.0 )
0.0
> y = {{alias}}( NaN, 1.0 )
NaN
> y = {{alias}}( 0.0, NaN )
NaN
// Negative mean parameter:
> y = {{alias}}( 2.0, -1.0 )
NaN
// Degenerate distribution at `λ = 0`:
> y = {{alias}}( -2.0, 0.0 )
0.0
> y = {{alias}}( 0.0, 0.0 )
1.0
> y = {{alias}}( 10.0, 0.0 )
1.0
{{alias}}.factory( λ )
Returns a function for evaluating the cumulative distribution function (CDF)
of a Poisson distribution with mean parameter `λ`.
Parameters
----------
λ: number
Mean parameter.
Returns
-------
cdf: Function
Cumulative distribution function (CDF).
Examples
--------
> var mycdf = {{alias}}.factory( 5.0 );
> var y = mycdf( 3.0 )
~0.265
> y = mycdf( 8.0 )
~0.932
See Also
--------