Last change
on this file since 351 was 337, checked in by coas-nagasima, 6 years ago |
ASP3版ECNLを追加
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Property svn:eol-style
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native
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Property svn:mime-type
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File size:
747 bytes
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1 | #include "libm.h"
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2 |
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3 | #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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4 | long double atanhl(long double x)
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5 | {
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6 | return atanh(x);
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7 | }
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8 | #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
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9 | /* atanh(x) = log((1+x)/(1-x))/2 = log1p(2x/(1-x))/2 ~= x + x^3/3 + o(x^5) */
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10 | long double atanhl(long double x)
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11 | {
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12 | union ldshape u = {x};
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13 | unsigned e = u.i.se & 0x7fff;
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14 | unsigned s = u.i.se >> 15;
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15 |
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16 | /* |x| */
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17 | u.i.se = e;
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18 | x = u.f;
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19 |
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20 | if (e < 0x3ff - 1) {
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21 | if (e < 0x3ff - LDBL_MANT_DIG/2) {
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22 | /* handle underflow */
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23 | if (e == 0)
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24 | FORCE_EVAL((float)x);
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25 | } else {
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26 | /* |x| < 0.5, up to 1.7ulp error */
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27 | x = 0.5*log1pl(2*x + 2*x*x/(1-x));
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28 | }
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29 | } else {
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30 | /* avoid overflow */
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31 | x = 0.5*log1pl(2*(x/(1-x)));
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32 | }
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33 | return s ? -x : x;
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34 | }
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35 | #endif
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