source: sasmodels/sasmodels/models/star_polymer.c @ 58c3367

core_shell_microgelscostrafo411magnetic_modelrelease_v0.94release_v0.95ticket-1257-vesicle-productticket_1156ticket_1265_superballticket_822_more_unit_tests
Last change on this file since 58c3367 was 2c74c11, checked in by Paul Kienzle <pkienzle@…>, 8 years ago

implicit Iqxy; fix divide by 0 for q=0

  • Property mode set to 100644
File size: 557 bytes
Line 
1double form_volume(void);
2
3double Iq(double q, double radius2, double arms);
4
5static double _mass_fractal_kernel(double q, double radius2, double arms)
6{
7
8    double u_2 = radius2 * pow(q,2);
9    double v = u_2 * arms / (3.0 * arms - 2.0);
10
11    double term1 = v - 1.0 + exp(-v);
12    double term2 = ((arms - 1.0)/2.0)* pow((1.0 - exp(-v)),2.0);
13
14    return (2.0 * (term1 + term2)) / (arms * pow(v,2.0));
15
16}
17
18double form_volume(void)
19{
20    return 1.0;
21}
22
23double Iq(double q, double radius2, double arms)
24{
25    return _mass_fractal_kernel(q, radius2, arms);
26}
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