source: sasview/src/sas/models/CorrLengthModel.py @ 7eaf9f2

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Last change on this file since 7eaf9f2 was 79492222, checked in by krzywon, 10 years ago

Changed the file and folder names to remove all SANS references.

  • Property mode set to 100644
File size: 3.2 KB
Line 
1#!/usr/bin/env python
2"""
3CorrLengthModel function as a BaseComponent model
4"""
5
6from sas.models.BaseComponent import BaseComponent
7from numpy import power
8import math
9
10class CorrLengthModel(BaseComponent):
11    """
12    Class that evaluates a CorrLengthModel.
13    I(q) = I(q) = scale_p/pow(q,exponent)+scale_l/
14    (1.0 + pow((q*length_l),exponent_l) )+ background
15    """
16       
17    def __init__(self):
18        """ Initialization """
19       
20        # Initialize BaseComponent first, then sphere
21        BaseComponent.__init__(self)
22       
23        ## Name of the model
24        self.name = "CorrLength"
25        self.description = """I(q) = scale_p/pow(q,exponent)+scale_l/
26            (1.0 + pow((q*length_l),exponent_l) )+ background
27             List of default parameters:
28             scale_p = Porod term scaling
29             exponent_p = Porod exponent
30             scale_l = Lorentzian term scaling
31             length_l = Lorentzian screening length [A]
32             exponent_l = Lorentzian exponent
33             background = Incoherent background
34        """
35        ## Define parameters
36        self.params = {}
37        self.params['scale_p']  = 1.0e-06
38        self.params['exponent_p']     = 3.0
39        self.params['scale_l']  = 10.0
40        self.params['length_l']     = 50.0
41        self.params['exponent_l']     = 2.0
42        self.params['background']     = 0.1
43        ## Parameter details [units, min, max]
44        self.details = {}
45        self.details['scale_p'] = ['', None, None]
46        self.details['exponent_p'] =  ['', None, None]
47        self.details['scale_l']  =  ['', None, None]
48        self.details['length_l']  =   ['A', None, None]
49        self.details['exponent_l']  =   ['', None, None]
50        self.details['background']   =  ['[1/cm]', None, None]
51
52        #list of parameter that cannot be fitted
53        self.fixed = [] 
54    def _corrlength(self, x):
55        """
56        Model definition
57        """
58        inten = self.params['scale_p']/pow(x, self.params['exponent_p'])
59        inten += self.params['scale_l']/(1.0 + \
60                power((x*self.params['length_l']), self.params['exponent_l']))
61        inten += self.params['background']
62
63        return inten 
64   
65    def run(self, x = 0.0):
66        """
67        Evaluate the model
68       
69        param x: input q-value (float or [float, float] as [r, theta])
70        return: (scattering value)
71        """
72        if x.__class__.__name__ == 'list':
73            return self._corrlength(x[0])
74        elif x.__class__.__name__ == 'tuple':
75            raise ValueError, "Tuples are not allowed as input to models"
76        else:
77            return self._corrlength(x)
78   
79    def runXY(self, x = 0.0):
80        """
81        Evaluate the model
82       
83        param x: input q-value (float or [float, float] as [qx, qy])
84        return: scattering value
85        """
86        if x.__class__.__name__ == 'list':
87            q = math.sqrt(x[0]**2 + x[1]**2)
88            return self._corrlength(q)
89        elif x.__class__.__name__ == 'tuple':
90            raise ValueError, "Tuples are not allowed as input to models"
91        else:
92            return self._corrlength(x)
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