Changeset c5607fa in sasview for sansmodels/src/sans/models/c_extensions

Timestamp:

Dec 1, 2009 8:39:26 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_extensions/schulz.c (modified) (5 diffs)

sansmodels/src/sans/models/c_extensions/schulz.c

@@ -12 +12 @@
  * Function to evaluate 1D Schulz function.
  * The function is normalized to the 'scale' parameter.
- * 
+ *
  * f(x)=scale * math.pow(z+1, z+1)*math.pow((R), z)*
  *                                      math.exp(-R*(z+1))/(center*gamma(z+1)
@@ -22 +22 @@
  */
 double schulz_analytical_1D(SchulzParameters *pars, double x) {
-        double z = pow(pars->center/ pars->sigma, 2)-1; 
+        double z = pow(pars->center/ pars->sigma, 2)-1;
         double R= x/pars->center;
         double zz= z+1;
-        return pars->scale * pow(zz,zz) * pow(R,z) * exp(-1*R*zz)/((pars->center) * tgamma(zz)) ;
+        double expo;
+        expo = log(pars->scale)+zz*log(zz)+z*log(R)-R*zz-log(pars->center)-lgamma(zz);
+
+        return exp(expo);//pars->scale * pow(zz,zz) * pow(R,z) * exp(-1*R*zz)/((pars->center) * tgamma(zz)) ;
 }
 
@@ -31 +34 @@
  * Function to evaluate 2D schulz function
  * The function is normalized to the 'scale' parameter.
- * 
+ *
  * f(x,y) = Schulz(x) * Schulz(y)
- * 
+ *
  * where both Shulzs share the same parameters.
- * 
+ *
  * @param pars: parameters of the schulz
  * @param x: x-value
@@ -43 +46 @@
 double schulz_analytical_2DXY(SchulzParameters *pars, double x, double y) {
     return schulz_analytical_1D(pars, x) * schulz_analytical_1D(pars, y);
-} 
+}
 
 /**
  * Function to evaluate 2D Schulz  function
  * The function is normalized to the 'scale' parameter.
- * 
+ *
  * f(x,y) = Schulz(x) * Schulz(y)
- * 
+ *
  * where both Gaussians share the same parameters.
- * 
+ *
  * @param pars: parameters of the gaussian
  * @param length: length of the (x,y) vector
@@ -60 +63 @@
 double schulz_analytical_2D(SchulzParameters *pars, double length, double phi) {
     return schulz_analytical_2DXY(pars, length*cos(phi), length*sin(phi));
-} 
+}