1 | /* ef_cosh.c -- float version of e_cosh.c. |
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2 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
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3 | */ |
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4 | |
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5 | /* |
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6 | * ==================================================== |
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7 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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8 | * |
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9 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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10 | * Permission to use, copy, modify, and distribute this |
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11 | * software is freely granted, provided that this notice |
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12 | * is preserved. |
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13 | * ==================================================== |
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14 | */ |
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15 | |
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16 | #include "fdlibm.h" |
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17 | |
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18 | #ifdef __v810__ |
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19 | #define const |
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20 | #endif |
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21 | |
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22 | #ifdef __STDC__ |
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23 | static const float one = 1.0, half=0.5, huge = 1.0e30; |
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24 | #else |
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25 | static float one = 1.0, half=0.5, huge = 1.0e30; |
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26 | #endif |
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27 | |
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28 | #ifdef __STDC__ |
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29 | float __ieee754_coshf(float x) |
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30 | #else |
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31 | float __ieee754_coshf(x) |
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32 | float x; |
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33 | #endif |
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34 | { |
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35 | float t,w; |
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36 | __int32_t ix; |
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37 | |
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38 | GET_FLOAT_WORD(ix,x); |
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39 | ix &= 0x7fffffff; |
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40 | |
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41 | /* x is INF or NaN */ |
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42 | if(!FLT_UWORD_IS_FINITE(ix)) return x*x; |
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43 | |
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44 | /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */ |
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45 | if(ix<0x3eb17218) { |
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46 | t = expm1f(fabsf(x)); |
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47 | w = one+t; |
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48 | if (ix<0x24000000) return w; /* cosh(tiny) = 1 */ |
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49 | return one+(t*t)/(w+w); |
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50 | } |
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51 | |
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52 | /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */ |
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53 | if (ix < 0x41b00000) { |
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54 | t = __ieee754_expf(fabsf(x)); |
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55 | return half*t+half/t; |
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56 | } |
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57 | |
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58 | /* |x| in [22, log(maxdouble)] return half*exp(|x|) */ |
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59 | if (ix <= FLT_UWORD_LOG_MAX) |
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60 | return half*__ieee754_expf(fabsf(x)); |
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61 | |
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62 | /* |x| in [log(maxdouble), overflowthresold] */ |
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63 | if (ix <= FLT_UWORD_LOG_2MAX) { |
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64 | w = __ieee754_expf(half*fabsf(x)); |
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65 | t = half*w; |
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66 | return t*w; |
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67 | } |
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68 | |
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69 | /* |x| > overflowthresold, cosh(x) overflow */ |
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70 | return huge*huge; |
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71 | } |
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