72 lines
1.4 KiB
Plaintext
72 lines
1.4 KiB
Plaintext
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{{alias}}( x, λ )
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Evaluates the natural logarithm of the probability mass function (PMF) for a
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Poisson distribution with mean parameter `λ` at a value `x`.
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If provided `NaN` as any argument, the function returns `NaN`.
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If provided a negative value for `λ`, the function returns `NaN`.
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Parameters
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----------
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x: number
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Input value.
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λ: number
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Mean parameter.
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Returns
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-------
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out: number
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Evaluated logPMF.
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Examples
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--------
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> var y = {{alias}}( 4.0, 3.0 )
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~-1.784
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> y = {{alias}}( 1.0, 3.0 )
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~-1.901
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> y = {{alias}}( -1.0, 2.0 )
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-Infinity
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> y = {{alias}}( 0.0, NaN )
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NaN
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> y = {{alias}}( NaN, 0.5 )
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NaN
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// Negative mean parameter:
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> y = {{alias}}( 2.0, -0.5 )
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NaN
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// Degenerate distribution at `λ = 0`:
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> y = {{alias}}( 2.0, 0.0 )
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-Infinity
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> y = {{alias}}( 0.0, 0.0 )
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0.0
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{{alias}}.factory( λ )
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Returns a function for evaluating the natural logarithm of the probability
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mass function (PMF) of a Poisson distribution with mean parameter `λ`.
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Parameters
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----------
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λ: number
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Mean parameter.
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Returns
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-------
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logpmf: Function
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Logarithm of probability mass function (PMF).
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Examples
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--------
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> var mylogpmf = {{alias}}.factory( 1.0 );
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> var y = mylogpmf( 3.0 )
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~-2.792
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> y = mylogpmf( 1.0 )
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~-1.0
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See Also
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--------
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