[829eee9] | 1 | #!/usr/bin/env python |
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| 2 | """ |
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[3db3895] | 3 | Provide F(x) = scale* (x)^(-m) + bkd |
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| 4 | Power law function as a BaseComponent model |
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[829eee9] | 5 | """ |
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| 6 | |
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| 7 | from sans.models.BaseComponent import BaseComponent |
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| 8 | import math |
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| 9 | |
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| 10 | class PowerLawModel(BaseComponent): |
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| 11 | |
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| 12 | """ |
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| 13 | Class that evaluates a Power_Law model. |
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| 14 | |
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[3db3895] | 15 | F(x) = scale* (x)^(-m) + bkd |
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[829eee9] | 16 | |
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| 17 | The model has three parameters: |
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| 18 | m = power |
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| 19 | scale = scale factor |
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| 20 | bkd = incoherent background |
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| 21 | """ |
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| 22 | |
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| 23 | def __init__(self): |
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| 24 | """ Initialization """ |
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| 25 | |
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| 26 | # Initialize BaseComponent first, then sphere |
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| 27 | BaseComponent.__init__(self) |
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| 28 | |
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| 29 | ## Name of the model |
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| 30 | self.name = "Power_Law" |
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| 31 | |
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| 32 | ## Define parameters |
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| 33 | self.params = {} |
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[3db3895] | 34 | self.params['m'] = 4.0 |
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| 35 | self.params['scale'] = 1.0 |
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| 36 | self.params['background'] = 0.0 |
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[829eee9] | 37 | |
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| 38 | ## Parameter details [units, min, max] |
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| 39 | self.details = {} |
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[3db3895] | 40 | self.details['m'] = ['', None, None ] |
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| 41 | self.details['scale'] = ['', None, None] |
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| 42 | self.details['background'] = ['', None, None] |
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[829eee9] | 43 | |
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| 44 | def _PowerLaw(self, x): |
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| 45 | """ |
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[3db3895] | 46 | Evaluate F(x) = scale* (x)^(-m) + bkd |
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[829eee9] | 47 | |
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| 48 | """ |
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[3db3895] | 49 | return self.params['scale']*math.pow(x ,-self.params['m'])\ |
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| 50 | + self.params['background'] |
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[829eee9] | 51 | |
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| 52 | |
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| 53 | def run(self, x = 0.0): |
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| 54 | """ Evaluate the model |
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[3db3895] | 55 | @param x: input q-value (float or [float, float] as [r, theta]) |
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[829eee9] | 56 | @return: (PowerLaw value) |
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| 57 | """ |
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| 58 | if x.__class__.__name__ == 'list': |
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| 59 | return self._PowerLaw(x[0]*math.cos(x[1]))*self._PowerLaw(x[0]*math.sin(x[1])) |
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| 60 | elif x.__class__.__name__ == 'tuple': |
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| 61 | raise ValueError, "Tuples are not allowed as input to BaseComponent models" |
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| 62 | else: |
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| 63 | return self._PowerLaw(x) |
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| 64 | |
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| 65 | def runXY(self, x = 0.0): |
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| 66 | """ Evaluate the model |
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[3db3895] | 67 | @param x: input q-value (float or [float, float] as [qx, qy]) |
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[829eee9] | 68 | @return: PowerLaw value |
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| 69 | """ |
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| 70 | if x.__class__.__name__ == 'list': |
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| 71 | return self._PowerLaw(x[0])*self._PowerLaw(x[1]) |
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| 72 | elif x.__class__.__name__ == 'tuple': |
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| 73 | raise ValueError, "Tuples are not allowed as input to BaseComponent models" |
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| 74 | else: |
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| 75 | return self._PowerLaw(x) |
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