Last change
on this file since 388 was 388, checked in by coas-nagasima, 5 years ago |
Azure IoT Hub Device C SDK を使ったサンプルの追加
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Property svn:eol-style
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native
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Property svn:keywords
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Id
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Property svn:mime-type
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text/x-csrc
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File size:
717 bytes
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[388] | 1 | #include "libm.h"
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| 2 |
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| 3 | /* asinh(x) = sign(x)*log(|x|+sqrt(x*x+1)) ~= x - x^3/6 + o(x^5) */
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| 4 | float asinhf(float x)
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| 5 | {
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| 6 | union {float f; uint32_t i;} u = {.f = x};
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| 7 | uint32_t i = u.i & 0x7fffffff;
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| 8 | unsigned s = u.i >> 31;
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| 9 |
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| 10 | /* |x| */
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| 11 | u.i = i;
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| 12 | x = u.f;
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| 13 |
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| 14 | if (i >= 0x3f800000 + (12<<23)) {
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| 15 | /* |x| >= 0x1p12 or inf or nan */
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| 16 | x = logf(x) + 0.693147180559945309417232121458176568f;
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| 17 | } else if (i >= 0x3f800000 + (1<<23)) {
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| 18 | /* |x| >= 2 */
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| 19 | x = logf(2*x + 1/(sqrtf(x*x+1)+x));
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| 20 | } else if (i >= 0x3f800000 - (12<<23)) {
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| 21 | /* |x| >= 0x1p-12, up to 1.6ulp error in [0.125,0.5] */
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| 22 | x = log1pf(x + x*x/(sqrtf(x*x+1)+1));
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| 23 | } else {
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| 24 | /* |x| < 0x1p-12, raise inexact if x!=0 */
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| 25 | FORCE_EVAL(x + 0x1p120f);
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| 26 | }
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| 27 | return s ? -x : x;
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| 28 | }
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