PoissonErrorDistribution = class PoissonErrorDistribution(ErrorDistribution) |
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PoissonErrorDistribution(copy=None)
To calculate a Poisson likelihood.
For one observation with n counts it holds
f( n,x ) = x^n / ( e^x * n! )
where x is the expected counts
The function is mostly used to calculate the likelihood L, or easier
to use log likelihood, logL.
logL = ∑( n * log( x ) - x - log( n! ) )
Weights are not accepted in this ErrorDistribution; they are silently ignored.
Author Do Kester. |
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- Method resolution order:
- PoissonErrorDistribution
- ErrorDistribution
- builtins.object
Constructor:
- PoissonErrorDistribution( copy=None )
- Constructor.
Parameters
----------
copy : PoissonErrorDistribution
distribution to be copied.
Methods defined here:
- acceptWeight()
- True if the distribution accepts weights.
Always false for this distribution.
- copy()
- Return copy of this.
- getScale( problem, allpars=None )
- Return the noise scale.
*** Gaussian approximation ***
Parameters
----------
problem : Problem
to be solved
allpars : array_like
None take parameters from problem.model
list of all parameters in the problem
- logLdata( problem, allpars, mockdata=None )
- Return the log( likelihood ) for each residual
logL = sum( logLdata )
Parameters
----------
problem : Problem
to be solved
allpars : array_like
list of all parameters in the problem
mockdata : array_like
as calculated by the model
- logLikelihood_alt( problem, allpars )
- Return the log( likelihood ) for a Poisson distribution.
Parameters
----------
problem : Problem
to be solved
allpars : array_like
list of all parameters in the problem
- nextPartialData( problem, allpars, fitIndex, mockdata=None )
- Return the partial derivative of log( likelihood ) to the parameters.
Parameters
----------
problem : Problem
to be solved
allpars : array_like
list of all parameters in the problem
fitIndex : array_like
indices of parameters to be fitted
mockdata : array_like
as calculated by the model
- partialLogL_alt( problem, allpars, fitIndex )
- Return the partial derivative of log( likelihood ) to the parameters.
Parameters
----------
problem : Problem
to be solved
allpars : array_like
list of all parameters in the problem
fitIndex : array_like
indices of parameters to be fitted
Methods inherited from ErrorDistribution:
- domain2Unit( dval, ks )
- getChisq( problem, allpars=None )
- getGaussianScale( problem, allpars=None )
- getResiduals( problem, allpars=None )
- hyparname( k )
- isBound()
- keepFixed( fixed=None )
- logCLhood( problem, allpars )
- logLhood( problem, allpars )
- numPartialLogL( problem, allpars, fitIndex )
- partialLogL( problem, allpars, fitIndex )
- setLimits( limits )
- setPriors( priors )
- setResult()
- toSigma( scale )
- unit2Domain( uval, ks )
- updateLogL( problem, allpars, parval=None )
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