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Revision 1440, 0.5 kB
(checked in by smidl, 14 years ago)
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rychly exp + vice clenu randn
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| 1 | /* fast approximation of the exp function according to: |
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| 2 | * NN Schraudolph, A fast, compact approximation of the exponential function, Neural Computation, 1999 |
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| 3 | */ |
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| 4 | |
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| 5 | #include <math.h> |
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| 6 | static union |
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| 7 | { |
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| 8 | double d; |
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| 9 | struct |
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| 10 | { |
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| 11 | /*#ifdef LITTLE_ENDIAN -- PC & TMS2812 !!!*/ |
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| 12 | int j, i; |
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| 13 | /*#else |
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| 14 | int i, j; |
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| 15 | #endif */ |
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| 16 | } n; |
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| 17 | } _eco; |
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| 18 | #define EXP_A (1048576 /M_LN2) |
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| 19 | /* #define EXP_C 60801 |
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| 20 | */ |
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| 21 | #define EXP_C 45799 |
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| 22 | |
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| 23 | /* use 1512775 for integer version */ |
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| 24 | /* see text for choice of c values */ |
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| 25 | #define EXP(y) (_eco.n.i = EXP_A*(y) + (1072693248 - EXP_C), _eco.d) |
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