core_shell_microgelscostrafo411magnetic_modelrelease_v0.94release_v0.95ticket-1257-vesicle-productticket_1156ticket_1265_superballticket_822_more_unit_tests
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Last change
on this file since ff7119b was
ff7119b,
checked in by Paul Kienzle <pkienzle@…>, 10 years ago
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docu update
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Property mode set to
100644
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File size:
796 bytes
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| 1 | // Compute the form factor for a cylinder |
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| 2 | // F^2(q) sin a |
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| 3 | // given |
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| 4 | // F(q) = sin(Q L/2 cos a)/(Q L/2 cos a) * 2 J1(Q R sin a) / (Q R sin a) |
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| 5 | // q is the q-value for the calculation (1/A) |
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| 6 | // radius is the radius of the cylinder (A) |
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| 7 | // halflength is the HALF-LENGTH of the cylinder = L/2 (A) |
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| 8 | real CylKernel(real q, real radius, real halflength, real theta); |
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| 9 | real CylKernel(real q, real radius, real halflength, real theta) |
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| 10 | { |
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| 11 | real sn, cn; |
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| 12 | SINCOS(theta, sn, cn); |
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| 13 | const real besarg = q*radius*sn; |
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| 14 | const real siarg = q*halflength*cn; |
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| 15 | // lim_{x->0} J1(x)/x = 1/2, lim_{x->0} sin(x)/x = 1 |
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| 16 | const real bj = (besarg == REAL(0.0) ? REAL(0.5) : J1(besarg)/besarg); |
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| 17 | const real si = (siarg == REAL(0.0) ? REAL(1.0) : sin(siarg)/siarg); |
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| 18 | return REAL(4.0)*sn*bj*bj*si*si; |
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| 19 | } |
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