source: sasview/sansmodels/src/sans/models/DABModel.py @ d292959

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Last change on this file since d292959 was 753552d, checked in by Gervaise Alina <gervyh@…>, 16 years ago

description added

  • Property mode set to 100644
File size: 2.7 KB
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1#!/usr/bin/env python
2"""
3    Provide F(x) = scale/( 1 + (x*L)^2 )^(2) + background
4    DAB (Debye Anderson Brumberger) function as a BaseComponent model
5"""
6
7from sans.models.BaseComponent import BaseComponent
8import math
9
10class DABModel(BaseComponent):
11   
12    """
13        Class that evaluates a DAB model.
14       
15        F(x) = scale/( 1 + (x*L)^2 )^(2) + background
16       
17        The model has three parameters:
18            L             =  Correlation Length
19            scale         =  scale factor
20            background    =  incoherent background
21    """
22       
23    def __init__(self):
24        """ Initialization """
25       
26        # Initialize BaseComponent first, then sphere
27        BaseComponent.__init__(self)
28       
29        ## Name of the model
30        self.name = "DAB_Model"
31        self.description="""F(x) = scale/( 1 + (x*L)^2 )^(2) + background
32       
33        The model has three parameters:
34        L             =  Correlation Length
35        scale         =  scale factor
36        background    =  incoherent background"""
37        ## Define parameters
38        self.params = {}
39        self.params['length']             = 50.0
40        self.params['scale']              = 1.0
41        self.params['background']         = 0.0
42
43        ## Parameter details [units, min, max]
44        self.details = {}
45        self.details['length']            = ['', None, None]
46        self.details['scale']             = ['', None, None]
47        self.details['background']        = ['', None, None]
48               
49    def _DAB(self, x):
50        """
51            Evaluate  F(x) = scale/( 1 + (x*L)^2 )^(2) + background
52           
53        """
54        return self.params['scale']/math.pow(( 1 + math.pow(x * self.params['length'],2)),2) \
55         + self.params['background']
56       
57   
58    def run(self, x = 0.0):
59        """ Evaluate the model
60            @param x: input q-value (float or [float, float] as [r, theta])
61            @return: (DAB value)
62        """
63        if x.__class__.__name__ == 'list':
64            return self._DAB(x[0])
65        elif x.__class__.__name__ == 'tuple':
66            raise ValueError, "Tuples are not allowed as input to BaseComponent models"
67        else:
68            return self._DAB(x)
69   
70    def runXY(self, x = 0.0):
71        """ Evaluate the model
72            @param x: input q-value (float or [float, float] as [qx, qy])
73            @return: DAB value
74        """
75        if x.__class__.__name__ == 'list':
76            q = math.sqrt(x[0]**2 + x[1]**2)
77            return self._DAB(q)
78        elif x.__class__.__name__ == 'tuple':
79            raise ValueError, "Tuples are not allowed as input to BaseComponent models"
80        else:
81            return self._DAB(x)
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