Changeset 36948c92 in sasview for sansmodels/src/sans/models/PowerLawModel.py

Timestamp:

Apr 15, 2008 8:08:40 AM (16 years ago)

Author:

Mathieu Doucet <doucetm@…>

Branches:

master, ESS_GUI, ESS_GUI_Docs, ESS_GUI_batch_fitting, ESS_GUI_bumps_abstraction, ESS_GUI_iss1116, ESS_GUI_iss879, ESS_GUI_iss959, ESS_GUI_opencl, ESS_GUI_ordering, ESS_GUI_sync_sascalc, costrafo411, magnetic_scatt, release-4.1.1, release-4.1.2, release-4.2.2, release_4.0.1, ticket-1009, ticket-1094-headless, ticket-1242-2d-resolution, ticket-1243, ticket-1249, ticket885, unittest-saveload

Children:

3de85b8

Parents:

5aa3bbd

Message:

Modified to testing and modified according to testing results

File:

• sansmodels/src/sans/models/PowerLawModel.py (modified) (3 diffs)

sansmodels/src/sans/models/PowerLawModel.py

@@ -38 +38 @@
         ## Parameter details [units, min, max]
         self.details = {}
-        self.details['m']           = ['', None, None ]
+        self.details['m']           = ['', 0,    None]
         self.details['scale']       = ['', None, None]
         self.details['background']  = ['', None, None]
@@ -47 +47 @@
            
         """
-        return self.params['scale']*math.pow(x ,-self.params['m'])\
+        if x<0 and self.params['m']>0:
+            raise ValueError, "negative number cannot be raised to a fractional power"
+        
+        return self.params['scale']*math.pow(x ,-1.0*self.params['m'])\
                 + self.params['background']
        
-   
     def run(self, x = 0.0):
         """ Evaluate the model
@@ -57 +59 @@
         """
         if x.__class__.__name__ == 'list':
-            return self._PowerLaw(x[0]*math.cos(x[1]))*self._PowerLaw(x[0]*math.sin(x[1]))
+            # Take absolute value of Q, since this model is really meant to
+            # be defined in 1D for a given length of Q
+            qx = math.fabs(x[0]*math.cos(x[1]))
+            qy = math.fabs(x[0]*math.sin(x[1]))
+            return self._PowerLaw(qx)*self._PowerLaw(qy)
         elif x.__class__.__name__ == 'tuple':
             raise ValueError, "Tuples are not allowed as input to BaseComponent models"