Changeset c5607fa in sasview for sansmodels/src/sans/models/c_models/parameters.cpp

Timestamp:

Dec 1, 2009 10:39:26 AM (15 years ago)

Author:

Jae Cho <jhjcho@…>

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:

437a9f0

Parents:

ef9ed58

Message:

Trick applied to the formula of Schulz func to fix having many singularities near small sigmas

File:

• sansmodels/src/sans/models/c_models/parameters.cpp (modified) (2 diffs)

sansmodels/src/sans/models/c_models/parameters.cpp

@@ -156 +156 @@
 
 double lognormal_weight(double mean, double sigma, double x) {
-        
-        double sigma2 = pow(sigma, 2);  
+
+        double sigma2 = pow(sigma, 2);
         return 1/(x*sigma2) * exp( -pow((log(x) -mean), 2) / (2*sigma2));
- 
+
 }
 
@@ -217 +217 @@
 double schulz_weight(double mean, double sigma, double x) {
         double vary, expo_value;
-    double z = pow(mean/ sigma, 2)-1;   
+    double z = pow(mean/ sigma, 2)-1;
         double R= x/mean;
         double zz= z+1;
-        return  pow(zz,zz) * pow(R,z) * exp(-1*R*zz)/((mean) * tgamma(zz)) ;
+        double expo;
+        expo = zz*log(zz)+z*log(R)-R*zz-log(mean)-lgamma(zz);
+        return  exp(expo);
 }