Source code for sas.models.GuinierModel

""" 
    Provide I(q) = I_0 exp ( - R_g^2 q^2 / 3.0)
    Guinier function as a BaseComponent model
"""
from sas.models.BaseComponent import BaseComponent
import math

[docs]class GuinierModel(BaseComponent): """ Class that evaluates a Guinier model. I(q) = I_0 exp ( - R_g^2 q^2 / 3.0 ) List of default parameters: I_0 = Scale R_g = Radius of gyration """ def __init__(self): """ Initialization """ # Initialize BaseComponent first, then sphere BaseComponent.__init__(self) ## Name of the model self.name = "Guinier" self.description = """ I(q) = I_0 exp ( - R_g^2 q^2 / 3.0 ) List of default parameters: I_0 = Scale R_g = Radius of gyration""" ## Define parameters self.params = {} self.params['scale'] = 1.0 self.params['rg'] = 60 ## Parameter details [units, min, max] self.details = {} self.details['scale'] = ['[1/cm]', None, None] self.details['rg'] = ['[A]', None, None] #list of parameter that cannot be fitted self.fixed = [] def _guinier(self, x): """ Evaluate guinier function :param x: q-value """ return self.params['scale']*math.exp( -(self.params['rg']*x)**2/3.0 )
[docs] def run(self, x = 0.0): """ Evaluate the model @param x: input q-value (float or [float, float] as [r, theta]) @return: (guinier value) """ if x.__class__.__name__ == 'list': return self._guinier(x[0]) elif x.__class__.__name__ == 'tuple': raise ValueError, "Tuples are not allowed as input to models" else: return self._guinier(x)
[docs] def runXY(self, x = 0.0): """ Evaluate the model @param x: input q-value (float or [float, float] as [qx, qy]) @return: guinier value """ if x.__class__.__name__ == 'list': q = math.sqrt(x[0]**2 + x[1]**2) return self._guinier(q) elif x.__class__.__name__ == 'tuple': raise ValueError, "Tuples are not allowed as input to models" else: return self._guinier(x)