Last change
on this file since 389 was 389, checked in by coas-nagasima, 5 years ago |
ビルドが通るよう更新
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File size:
605 bytes
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[388] | 1 | #include "libm.h"
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| 2 |
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| 3 | #if FLT_EVAL_METHOD==2
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| 4 | #undef sqrtf
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| 5 | #define sqrtf sqrtl
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| 6 | #elif FLT_EVAL_METHOD==1
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| 7 | #undef sqrtf
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| 8 | #define sqrtf sqrt
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| 9 | #endif
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| 10 |
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| 11 | /* acosh(x) = log(x + sqrt(x*x-1)) */
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| 12 | float acoshf(float x)
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| 13 | {
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| 14 | union {float f; uint32_t i;} u = {x};
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| 15 | uint32_t a = u.i & 0x7fffffff;
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| 16 |
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| 17 | if (a < 0x3f800000+(1<<23))
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| 18 | /* |x| < 2, invalid if x < 1 or nan */
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| 19 | /* up to 2ulp error in [1,1.125] */
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| 20 | return log1pf(x-1 + sqrtf((x-1)*(x-1)+2*(x-1)));
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| 21 | if (a < 0x3f800000+(12<<23))
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| 22 | /* |x| < 0x1p12 */
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| 23 | return logf(2*x - 1/(x+sqrtf(x*x-1)));
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| 24 | /* x >= 0x1p12 */
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| 25 | return logf(x) + 0.693147180559945309417232121458176568f;
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| 26 | }
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