Changeset ee60aa7 in sasmodels for explore/precision.py

Timestamp:

Sep 10, 2018 2:16:46 PM (6 years ago)

Author:

Paul Kienzle <pkienzle@…>

Branches:

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

Children:

d299327

Parents:

3f818b2

Message:

clean up effective radius functions; improve mono_gauss_coil accuracy; start moving VR into C

File:

• explore/precision.py (modified) (3 diffs)

explore/precision.py

@@ -357 +357 @@
 )
 add_function(
-    name="debye",
+    name="gauss_coil",
     mp_function=lambda x: 2*(mp.exp(-x**2) + x**2 - 1)/x**4,
     np_function=lambda x: 2*(np.expm1(-x**2) + x**2)/x**4,
     ocl_function=make_ocl("""
     const double qsq = q*q;
-    if (qsq < 1.0) { // Pade approximation
+    // For double: use O(5) Pade with 0.5 cutoff (10 mad + 1 divide)
+    // For single: use O(7) Taylor with 0.8 cutoff (7 mad)
+    if (qsq < 0.0) {
         const double x = qsq;
         if (0) { // 0.36 single
@@ -372 +374 @@
             const double B1=3./8., B2=3./56., B3=1./336.;
             return (((A3*x + A2)*x + A1)*x + 1.)/(((B3*x + B2)*x + B1)*x + 1.);
-        } else if (1) { // 1.0 for single, 0.25 for double
+        } else if (0) { // 1.0 for single, 0.25 for double
             // PadeApproximant[2*Exp[-x^2] + x^2-1)/x^4, {x, 0, 8}]
             const double A1=1./15., A2=1./60, A3=0., A4=1./75600.;
@@ -385 +387 @@
                   /(((((B5*x + B4)*x + B3)*x + B2)*x + B1)*x + 1.);
         }
-    } else if (qsq < 1.) { // Taylor series; 0.9 for single, 0.25 for double
+    } else if (qsq < 0.8) {
         const double x = qsq;
         const double C0 = +1.;