Changeset 36948c92 in sasview for sansmodels/src/sans/models/FractalModel.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/FractalModel.py (modified) (3 diffs)

sansmodels/src/sans/models/FractalModel.py

@@ -49 +49 @@
         ## Parameter details [units, min, max]
         self.details = {}
-        self.details['scale']       = ['', None, None]
-        self.details['radius']      = ['A', None, None]
-        self.details['fractal_dim'] = ['', None, None]
-        self.details['corr_length'] = ['A', None, None]
-        self.details['block_sld']   = ['A-2', None, None]
-        self.details['solvent_sld'] = ['A-2', None, None]
+        self.details['scale']       = ['',     None, None]
+        self.details['radius']      = ['A',    None, None]
+        self.details['fractal_dim'] = ['',       0,  None]
+        self.details['corr_length'] = ['A',    None, None]
+        self.details['block_sld']   = ['A-2',  None, None]
+        self.details['solvent_sld'] = ['A-2',  None, None]
         self.details['background']  = ['cm-1', None, None]
        
@@ -63 +63 @@
             F(x) = p(x) * s(x) + bkd  
         """
+        if x<0 and self.params['fractal_dim']>0:
+            raise ValueError, "negative number cannot be raised to a fractional power"
+
         return self.params['background']+ self._scatterRanDom(x)* self._Block(x)
+
     
     def _Block(self,x):
-        
-        
-        
         return 1.0 + (math.sin((self.params['fractal_dim']-1.0) * math.atan(x * self.params['corr_length']))\
              * self.params['fractal_dim'] * gamma(self.params['fractal_dim']-1.0))\
@@ -96 +97 @@
         """
         if x.__class__.__name__ == 'list':
-            return self._Fractal(x[0]*math.cos(x[1]))*self._Fractal(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._Fractal(qx)*self._Fractal(qy)
         elif x.__class__.__name__ == 'tuple':
             raise ValueError, "Tuples are not allowed as input to BaseComponent models"