Changeset ff7119b in sasmodels for sasmodels/models/lib/cylkernel.c

Timestamp:

Aug 26, 2014 8:27:06 PM (10 years ago)

Author:

Paul Kienzle <pkienzle@…>

Branches:

master, core_shell_microgels, costrafo411, magnetic_model, release_v0.94, release_v0.95, ticket-1257-vesicle-product, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests

Children:

5d4777d

Parents:

a7684e5

Message:

docu update

File:

• sasmodels/models/lib/cylkernel.c (modified) (1 diff)

sasmodels/models/lib/cylkernel.c

@@ -1 +1 @@
 // Compute the form factor for a cylinder
-// qq is the q-value for the calculation (1/A)
+//     F^2(q) sin a
+// given
+//     F(q) = sin(Q L/2 cos a)/(Q L/2 cos a) * 2 J1(Q R sin a) / (Q R sin a)
+// q is the q-value for the calculation (1/A)
 // radius is the radius of the cylinder (A)
-// h is the HALF-LENGTH of the cylinder = L/2 (A)
-real CylKernel(real q, real radius, real h, real theta);
-real CylKernel(real q, real radius, real h, real theta)
+// halflength is the HALF-LENGTH of the cylinder = L/2 (A)
+real CylKernel(real q, real radius, real halflength, real theta);
+real CylKernel(real q, real radius, real halflength, real theta)
 {
     real sn, cn;
     SINCOS(theta, sn, cn);
     const real besarg = q*radius*sn;
-    const real siarg = q*h*cn;
+    const real siarg = q*halflength*cn;
     // lim_{x->0} J1(x)/x = 1/2,  lim_{x->0} sin(x)/x = 1
     const real bj = (besarg == REAL(0.0) ? REAL(0.5) : J1(besarg)/besarg);
     const real si = (siarg == REAL(0.0) ? REAL(1.0) : sin(siarg)/siarg);
-    return REAL(4.0)*sin(theta)*bj*bj*si*si;
+    return REAL(4.0)*sn*bj*bj*si*si;
 }