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 e6f1410 was
e6f1410,
checked in by Paul Kienzle <pkienzle@…>, 7 years ago
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examine numerical precision of J1c, sinc, j1c and log gamma
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-
Property mode set to
100644
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File size:
542 bytes
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| 1 | double lanczos_gamma(double q); |
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| 2 | double lanczos_gamma(double q) |
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| 3 | { |
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| 4 | // Lanczos approximation to the Log Gamma function. |
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| 5 | |
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| 6 | double x,y,tmp,ser; |
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| 7 | double coeff[6]= |
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| 8 | {76.18009172947146, -86.50532032941677, |
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| 9 | 24.01409824083091, -1.231739572450155, |
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| 10 | 0.1208650973866179e-2,-0.5395239384953e-5}; |
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| 11 | |
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| 12 | y=x=q; |
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| 13 | tmp = x+5.5; |
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| 14 | tmp -= (x+0.5)*log(tmp); |
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| 15 | ser = 1.000000000190015; |
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| 16 | for (int j=0; j<=5; j++) { |
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| 17 | y+=1.0; |
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| 18 | ser += coeff[j]/y; |
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| 19 | } |
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| 20 | return -tmp+log(2.5066282746310005*ser/x); |
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| 21 | } |
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