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 f12357f was
f12357f,
checked in by krzywon, 8 years ago
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Modified the pearl_necklace model for better double precision accuracy
and added unit tests.
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-
Property mode set to
100644
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File size:
718 bytes
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| 1 | double Si(double x); |
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| 2 | |
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| 3 | // integral of sin(x)/x Taylor series approximated to w/i 0.1% |
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| 4 | double Si(double x) |
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| 5 | { |
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| 6 | double out; |
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| 7 | double pi = 4.0*atan(1.0); |
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| 8 | |
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| 9 | if (x >= pi*6.2/4.0){ |
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| 10 | double out_sin = 0.0; |
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| 11 | double out_cos = 0.0; |
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| 12 | out = pi/2.0; |
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| 13 | |
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| 14 | // Explicitly writing factorial values triples the speed of the calculation |
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| 15 | out_cos = 1./x - 2./pow(x,3) + 24./pow(x,5) - 720./pow(x,7); |
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| 16 | out_sin = 1./pow(x,2) - 6./pow(x,4) + 120./pow(x,6) - 5040./pow(x,8); |
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| 17 | |
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| 18 | out -= cos(x) * out_cos; |
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| 19 | out -= sin(x) * out_sin; |
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| 20 | return out; |
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| 21 | } |
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| 22 | |
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| 23 | // Explicitly writing factorial values triples the speed of the calculation |
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| 24 | out = x - pow(x, 3)/18. + pow(x,5)/600. - pow(x,7)/35280. + pow(x,9)/3265920. - pow(x,11)/439084800.; |
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| 25 | |
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| 26 | return out; |
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| 27 | } |
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