Changeset 0ad5703 in sasview for sansmodels/src/sans/models

Timestamp:

Mar 24, 2011 4:11:05 PM (14 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:

389c991

Parents:

50764a4

Message:

PD correction on lognormal distribution

File:

• sansmodels/src/sans/models/c_models/parameters.cpp (modified) (7 diffs)

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

@@ -160 +160 @@
         npts  = 11;
         width = 0.0;
-        nsigmas = 1.0;
+        nsigmas = 1.73205;
 };
 
@@ -172 +172 @@
 double rectangle_weight(double mean, double sigma, double x) {
         double vary, expo_value;
-    double sig = fabs(sigma);
-    if (x>= (mean-sig) && x<(mean+sig)){
+    double wid = fabs(sigma) * sqrt(3.0);
+    if (x>= (mean-wid) && x<=(mean+wid)){
         return 1.0;
     }
@@ -193 +193 @@
                 width = 0.0;
                 npts  = 1;
-                nsigmas = 1.0;
+                nsigmas = 1.73205;
         }
 
@@ -228 +228 @@
 
 LogNormalDispersion :: LogNormalDispersion() {
-        npts  = 11;
+        npts  = 15;
         width = 0.0;
-        nsigmas = 3.0;
+        nsigmas = 4.0;
 };
 
@@ -243 +243 @@
 
         double sigma2 = pow(sigma, 2.0);
-        return 1.0/(x*sigma2) * exp( -pow((log(x) -mean), 2.0) / (2.0*sigma2));
+        return 1.0/(x*sigma) * exp( -pow((log(x) -log(mean)), 2.0) / (2.0*sigma2));
 
 }
@@ -259 +259 @@
                 width = 0.0;
                 npts  = 1;
-                nsigmas = 3.0;
+                nsigmas = 4.0;
         }
 
@@ -269 +269 @@
         } else {
                 for(int i=0; i<npts; i++) {
+                        // Note that the definition of sigma is different from Gaussian
                         if ((*par).has_min==false){
-                                // width = sigma for angles
+                                // sig  for angles
+                                sig = width / value;
+                        }
+                        else{
+                                // by lognormal definition, PD is same as sigma
                                 sig = width;
                         }
-                        else{
-                                //width = polydispersity (=sigma/value) for length
-                                sig = width * value;
-                        }
+
                         // We cover n(nsigmas) times sigmas on each side of the mean
                         double val = value + sig * (2.0*nsigmas*double(i)/double(npts-1) - nsigmas);