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path: root/src/math/asinl.c
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 ```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 ``` ``````/* origin: FreeBSD /usr/src/lib/msun/src/e_asinl.c */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunSoft, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ /* * See comments in asin.c. * Converted to long double by David Schultz . */ #include "libm.h" #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024 long double asinl(long double x) { return asin(x); } #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384 #include "__invtrigl.h" /* 0.95 */ #define THRESH ((0xe666666666666666ULL>>(64-(LDBL_MANH_SIZE-1)))|LDBL_NBIT) long double asinl(long double x) { union IEEEl2bits u; long double z,r,s; uint16_t expsign, expt; u.e = x; expsign = u.xbits.expsign; expt = expsign & 0x7fff; if (expt >= 0x3fff) { /* |x| >= 1 or nan */ if (expt == 0x3fff && ((u.bits.manh&~LDBL_NBIT)|u.bits.manl) == 0) /* asin(+-1)=+-pi/2 with inexact */ return x*pio2_hi + 0x1p-1000; return 0/(x-x); } if (expt < 0x3fff - 1) { /* |x| < 0.5 */ if (expt < 0x3fff - 32) { /* |x|<0x1p-32, asinl(x)=x */ /* return x with inexact if x!=0 */ FORCE_EVAL(x + 0x1p1000); return x; } return x + x*__invtrigl_R(x*x); } /* 1 > |x| >= 0.5 */ z = (1.0 - fabsl(x))*0.5; s = sqrtl(z); r = __invtrigl_R(z); if (u.bits.manh >= THRESH) { /* if |x| is close to 1 */ x = pio2_hi - (2*(s+s*r)-pio2_lo); } else { long double f, c; u.e = s; u.bits.manl = 0; f = u.e; c = (z-f*f)/(s+f); x = 0.5*pio2_hi-(2*s*r - (pio2_lo-2*c) - (0.5*pio2_hi-2*f)); } if (expsign>>15) return -x; return x; } #endif ``````