Source code for sas.models.CorrLengthModel

#!/usr/bin/env python
""" 
CorrLengthModel function as a BaseComponent model
"""

from sas.models.BaseComponent import BaseComponent
from numpy import power
import math

[docs]class CorrLengthModel(BaseComponent): """ Class that evaluates a CorrLengthModel. I(q) = I(q) = scale_p/pow(q,exponent)+scale_l/ (1.0 + pow((q*length_l),exponent_l) )+ background """ def __init__(self): """ Initialization """ # Initialize BaseComponent first, then sphere BaseComponent.__init__(self) ## Name of the model self.name = "CorrLength" self.description = """I(q) = scale_p/pow(q,exponent)+scale_l/ (1.0 + pow((q*length_l),exponent_l) )+ background List of default parameters: scale_p = Porod term scaling exponent_p = Porod exponent scale_l = Lorentzian term scaling length_l = Lorentzian screening length [A] exponent_l = Lorentzian exponent background = Incoherent background """ ## Define parameters self.params = {} self.params['scale_p'] = 1.0e-06 self.params['exponent_p'] = 3.0 self.params['scale_l'] = 10.0 self.params['length_l'] = 50.0 self.params['exponent_l'] = 2.0 self.params['background'] = 0.1 ## Parameter details [units, min, max] self.details = {} self.details['scale_p'] = ['', None, None] self.details['exponent_p'] = ['', None, None] self.details['scale_l'] = ['', None, None] self.details['length_l'] = ['A', None, None] self.details['exponent_l'] = ['', None, None] self.details['background'] = ['[1/cm]', None, None] #list of parameter that cannot be fitted self.fixed = [] def _corrlength(self, x): """ Model definition """ inten = self.params['scale_p']/pow(x, self.params['exponent_p']) inten += self.params['scale_l']/(1.0 + \ power((x*self.params['length_l']), self.params['exponent_l'])) inten += self.params['background'] return inten
[docs] def run(self, x = 0.0): """ Evaluate the model param x: input q-value (float or [float, float] as [r, theta]) return: (scattering value) """ if x.__class__.__name__ == 'list': return self._corrlength(x[0]) elif x.__class__.__name__ == 'tuple': raise ValueError, "Tuples are not allowed as input to models" else: return self._corrlength(x)
[docs] def runXY(self, x = 0.0): """ Evaluate the model param x: input q-value (float or [float, float] as [qx, qy]) return: scattering value """ if x.__class__.__name__ == 'list': q = math.sqrt(x[0]**2 + x[1]**2) return self._corrlength(q) elif x.__class__.__name__ == 'tuple': raise ValueError, "Tuples are not allowed as input to models" else: return self._corrlength(x)