source: sasmodels/sasmodels/models/cylinder.c @ ee60aa7

core_shell_microgelsmagnetic_modelticket-1257-vesicle-productticket_1156ticket_1265_superballticket_822_more_unit_tests
Last change on this file since ee60aa7 was ee60aa7, checked in by Paul Kienzle <pkienzle@…>, 6 years ago

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

  • Property mode set to 100644
File size: 2.2 KB
Line 
1#define INVALID(v) (v.radius<0 || v.length<0)
2
3static double
4form_volume(double radius, double length)
5{
6    return M_PI*radius*radius*length;
7}
8
9static double
10_fq(double qab, double qc, double radius, double length)
11{
12    return sas_2J1x_x(qab*radius) * sas_sinx_x(qc*0.5*length);
13}
14
15static double
16radius_from_volume(double radius, double length)
17{
18    return cbrt(0.75*radius*radius*length);
19}
20
21static double
22radius_from_diagonal(double radius, double length)
23{
24    return sqrt(radius*radius + 0.25*length*length);
25}
26
27static double
28effective_radius(int mode, double radius, double length)
29{
30    switch (mode) {
31    case 1:
32        return radius_from_volume(radius, length);
33    case 2:
34        return radius;
35    case 3:
36        return 0.5*length;
37    case 4:
38        return (radius < 0.5*length ? radius : 0.5*length);
39    case 5:
40        return (radius > 0.5*length ? radius : 0.5*length);
41    case 6:
42        return radius_from_diagonal(radius,length);
43    }
44}
45
46static void
47Fq(double q,
48    double *F1,
49    double *F2,
50    double sld,
51    double solvent_sld,
52    double radius,
53    double length)
54{
55    // translate a point in [-1,1] to a point in [0, pi/2]
56    const double zm = M_PI_4;
57    const double zb = M_PI_4;
58
59    double total_F1 = 0.0;
60    double total_F2 = 0.0;
61    for (int i=0; i<GAUSS_N ;i++) {
62        const double theta = GAUSS_Z[i]*zm + zb;
63        double sin_theta, cos_theta; // slots to hold sincos function output
64        // theta (theta,phi) the projection of the cylinder on the detector plane
65        SINCOS(theta , sin_theta, cos_theta);
66        const double form = _fq(q*sin_theta, q*cos_theta, radius, length);
67        total_F1 += GAUSS_W[i] * form * sin_theta;
68        total_F2 += GAUSS_W[i] * form * form * sin_theta;
69    }
70    // translate dx in [-1,1] to dx in [lower,upper]
71    total_F1 *= zm;
72    total_F2 *= zm;
73    const double s = (sld - solvent_sld) * form_volume(radius, length);
74    *F1 = 1e-2 * s * total_F1;
75    *F2 = 1e-4 * s * s * total_F2;
76}
77
78
79
80static double
81Iqac(double qab, double qc,
82    double sld,
83    double solvent_sld,
84    double radius,
85    double length)
86{
87    const double form = _fq(qab, qc, radius, length);
88    const double s = (sld-solvent_sld) * form_volume(radius, length);
89    return 1.0e-4 * square(s * form);
90}
91
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