Changeset dbf1a60 in sasmodels for sasmodels/models/core_shell_parallelepiped.c

Timestamp:

Mar 11, 2018 2:29:41 PM (6 years ago)

Author:

butler

Branches:

master, core_shell_microgels, magnetic_model, ticket-1257-vesicle-product, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests

Children:

9616dfe

Parents:

367886f

Message:

Add comments to c code and clean documentatin

Added comments to c code in both parallelepiped and core shell
parallelepiped noting the change of integration varialbes in the
computation. Cleaned up and final corrections to the core shell
documentation and did some cleaning of parallelipiped. In particular
tried to bring a bit more consistency between the docs.

addresses #896

File:

• sasmodels/models/core_shell_parallelepiped.c (modified) (2 diffs)

sasmodels/models/core_shell_parallelepiped.c

@@ -59 +59 @@
 
     // outer integral (with gauss points), integration limits = 0, 1
+    // substitute d_cos_alpha for sin_alpha d_alpha
     double outer_sum = 0; //initialize integral
     for( int i=0; i<GAUSS_N; i++) {
         const double cos_alpha = 0.5 * ( GAUSS_Z[i] + 1.0 );
         const double mu = half_q * sqrt(1.0-cos_alpha*cos_alpha);
-
-        // inner integral (with gauss points), integration limits = 0, pi/2
         const double siC = length_c * sas_sinx_x(length_c * cos_alpha * half_q);
         const double siCt = tC * sas_sinx_x(tC * cos_alpha * half_q);
+
+        // inner integral (with gauss points), integration limits = 0, 1
+        // substitute beta = PI/2 u (so 2/PI * d_(PI/2 * beta) = d_beta)
         double inner_sum = 0.0;
         for(int j=0; j<GAUSS_N; j++) {
-            const double beta = 0.5 * ( GAUSS_Z[j] + 1.0 );
+            const double u = 0.5 * ( GAUSS_Z[j] + 1.0 );
             double sin_beta, cos_beta;
-            SINCOS(M_PI_2*beta, sin_beta, cos_beta);
+            SINCOS(M_PI_2*u, sin_beta, cos_beta);
             const double siA = length_a * sas_sinx_x(length_a * mu * sin_beta);
             const double siB = length_b * sas_sinx_x(length_b * mu * cos_beta);
@@ -91 +93 @@
             inner_sum += GAUSS_W[j] * f * f;
         }
+        // now complete change of inner integration variable (1-0)/(1-(-1))= 0.5
         inner_sum *= 0.5;
         // now sum up the outer integral
         outer_sum += GAUSS_W[i] * inner_sum;
     }
+    // now complete change of outer integration variable (1-0)/(1-(-1))= 0.5
     outer_sum *= 0.5;