source: sasview/sansmodels/src/sans/models/FractalAbsModel.py @ 71e2de7

#!/usr/bin/env python
""" 
    
    Provide F(x)= P(|x|)*S(|x|) + bkd
    Fractal as a BaseComponent model
"""

from sans.models.FractalModel import FractalModel
import math

class FractalAbsModel(FractalModel):
    """
        Class that evaluates a Fractal function.
        
        F(|x|)= P(|x|)*S(|x|) + bkd
        The model has Seven parameters: 
            scale        =  Volume fraction
            radius       =  Block radius
            fractal_dim  =  Fractal dimension
            corr_length  =  correlation Length
            block_sld    =  SDL block
            solvent_sld  =  SDL solvent
            background   =  background
           
    """
    def __init__(self):
        """ Initialization """
        # Initialize FractalModel 

        FractalModel.__init__(self)
        ## Name of the model
        self.name = "Absolute Number Density Fractal"
        self.description="""
        I(x)= P(|x|)*S(|x|) + bkd
        
        p(x)= scale* V^(2)*delta^(2)* F(x*radius)^(2)
        F(x) = 3*[sin(x)-x cos(x)]/x**3
        
        The model has Seven parameters: 
        scale        =  Volume fraction
        radius       =  Block radius
        fractal_dim  =  Fractal dimension
        corr_length  =  correlation Length
        block_sld    =  SDL block
        solvent_sld  =  SDL solvent
        background   =  background
        """
    def _Fractal(self, x):
        return FractalModel._Fractal(self, math.fabs(x))