source:
sasmodels/sasmodels/models/star_polymer.c
@
abb6e4f
Last change on this file since abb6e4f was 2586093f, checked in by Paul Kienzle <pkienzle@…>, 7 years ago | |
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File size: 537 bytes |
Rev | Line | |
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[55b283e8] | 1 | double form_volume(void); |
2 | ||
3 | double Iq(double q, double radius2, double arms); | |
4 | ||
[2586093f] | 5 | static double star_polymer_kernel(double q, double radius2, double arms) |
[55b283e8] | 6 | { |
7 | ||
[3a48772] | 8 | double u_2 = radius2 * q * q; |
[55b283e8] | 9 | double v = u_2 * arms / (3.0 * arms - 2.0); |
10 | ||
[3a48772] | 11 | double term1 = v + expm1(-v); |
12 | double term2 = ((arms - 1.0)/2.0) * square(expm1(-v)); | |
[55b283e8] | 13 | |
[3a48772] | 14 | return (2.0 * (term1 + term2)) / (arms * v * v); |
[55b283e8] | 15 | |
16 | } | |
17 | ||
18 | double form_volume(void) | |
19 | { | |
20 | return 1.0; | |
21 | } | |
22 | ||
23 | double Iq(double q, double radius2, double arms) | |
24 | { | |
[2586093f] | 25 | return star_polymer_kernel(q, radius2, arms); |
[55b283e8] | 26 | } |
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