interface

class zfit.minimizers.interface.ZfitMinimizer

Bases: object

Define the minimizer interface.

minimize(loss, params=None)

step(loss, params=None)

tolerance

class zfit.minimizers.interface.ZfitResult

Bases: object

error(params, method, sigma)

Calculate and set for params the asymmetric error using the set error method.

Parameters:

• params (list(zfit.FitParameters or str)) – The parameters or their names to calculate the errors. If params is None, use all floating parameters.
• method (str or Callable) – The method to use to calculate the errors. Valid choices are {‘minuit_minos’} or a Callable.

Returns:

A OrderedDict containing as keys the parameter names and as value a dict which

contains (next to probably more things) two keys ‘lower’ and ‘upper’, holding the calculated errors. Example: result[‘par1’][‘upper’] -> the asymmetric upper error of ‘par1’

Return type:

OrderedDict

fmin

hesse(params, method)

Calculate for params the symmetric error using the Hessian matrix.

Parameters:

• params (list(zfit.FitParameters)) – The parameters to calculate the Hessian symmetric error. If None, use all parameters.
• method (str) – the method to calculate the hessian. Can be {‘minuit’} or a callable.

Returns:

Result of the hessian (symmetric) error as dict with each parameter holding

the error dict {‘error’: sym_error}.

So given param_a (from zfit.Parameter(.)) error_a = result.hesse(params=param_a)[param_a][‘error’] error_a is the hessian error.

Return type:

OrderedDict

loss

minimizer

params