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/* |
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* Written 2005 by Gregory W. Chicares . |
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* Adapted to float by Danny Smith . |
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* Public domain. |
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* |
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* F2XM1's input is constrained to (-1, +1), so the domain of |
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* 'x * LOG2EL' is (-LOGE2L, +LOGE2L). Outside that domain, |
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* delegating to exp() handles C99 7.12.6.3/2 range errors. |
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* |
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* Constants from moshier.net, file cephes/ldouble/constl.c, |
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* are used instead of M_LN2 and M_LOG2E, which would not be |
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* visible with 'gcc std=c99'. The use of these extended precision |
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* constants also allows gcc to replace them with x87 opcodes. |
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*/ |
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#include /* expl() */ |
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#include "cephes_mconf.h" |
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float expm1f (float x) |
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{ |
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if (fabsf(x) < LOGE2L) |
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{ |
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x *= LOG2EL; |
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__asm__("f2xm1" : "=t" (x) : "0" (x)); |
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return x; |
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} |
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else |
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return expf(x) - 1.0F; |
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} |