BayesicFitting

Model Fitting and Evidence Calculation

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class MonteCarlo( object )Source

Helper class to calculate the confidence region of a fitted model.

MonteCarlo for models.

The MonteCarlo class is to be used in conjunction with Model classes.

Author: Do Kester

Attributes

  • xdata : array_like
         array of independent input values
  • model : Model
         the model function to be fitted
  • mcycles : int
         Sets number of cycles in the MonteCarlo procedure to estimate
         error bars. Default = 25

Hidden Attributes

  • _eigenvectors : array_like (read only)
         from eigenvalue decomposition of covariance matrix
  • _eigenvalues : array_like (read only)
         from eigenvalue decomposition of covariance matrix
  • _random : random
         random number generator

MonteCarlo( xdata, model, covariance, index=None, seed=12345, mcycles=25 )

Create a new MonteCarlo, providing inputs and model.

A MonteCarlo object is defined by its model and the input vector (the independent variable). When a fit to another model and/or another input vector is needed a new object should be created.

Parameters

  • xdata : array_like
         array of independent input values
  • model : Model
         the model function to be fitted
  • covariance : matrix
         the covariance matrix of the problem. Default from the Model.
  • index : list of int
         indices of parameters to fit
  • seed : int
         seed for random number generator
  • mcycles : int
         number of cycles in the MonteCarlo procedure to estimate error bars.

Raises

ValueError when model and input have different dimensions

decompose( covariance )

getError( xdata=None )
Calculates 1 σ-confidence regions on the model given some inputs.

From the full covariance matrix ( = inverse of the Hessian ) random samples are drawn, which are added to the parameters. With this new set of parameters the model is calculated. This procedure is done by default, 25 times. The standard deviation of the models is returned as the error bar.

Parameters

  • xdata : array_like
         input data over which to calculate the error bars. default provided xdata

randomVariant( xdata )
Return a random variant of the model result. Taking into account the stdev of the parameters and their covariance.

Parameters

  • xdata : array_like
         input data at these indpendent points