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Diffstat (limited to 'src/math/atanl.c')
-rw-r--r-- | src/math/atanl.c | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/src/math/atanl.c b/src/math/atanl.c new file mode 100644 index 00000000..4e99955e --- /dev/null +++ b/src/math/atanl.c @@ -0,0 +1,91 @@ +/* origin: FreeBSD /usr/src/lib/msun/src/s_atanl.c */ +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunPro, 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 atan.c. + * Converted to long double by David Schultz <das@FreeBSD.ORG>. + */ + +#include "libm.h" + +#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024 +long double atanl(long double x) +{ + return atan(x); +} +#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384 +#include "__invtrigl.h" +static const long double +one = 1.0, +huge = 1.0e300; + +long double atanl(long double x) +{ + union IEEEl2bits u; + long double w,s1,s2,z; + int id; + int16_t expsign, expt; + int32_t expman; + + u.e = x; + expsign = u.xbits.expsign; + expt = expsign & 0x7fff; + if (expt >= ATAN_CONST) { /* if |x| is large, atan(x)~=pi/2 */ + if (expt == BIAS + LDBL_MAX_EXP && + ((u.bits.manh&~LDBL_NBIT)|u.bits.manl)!=0) /* NaN */ + return x+x; + if (expsign > 0) + return atanhi[3]+atanlo[3]; + else + return -atanhi[3]-atanlo[3]; + } + /* Extract the exponent and the first few bits of the mantissa. */ + /* XXX There should be a more convenient way to do this. */ + expman = (expt << 8) | ((u.bits.manh >> (MANH_SIZE - 9)) & 0xff); + if (expman < ((BIAS - 2) << 8) + 0xc0) { /* |x| < 0.4375 */ + if (expt < ATAN_LINEAR) { /* if |x| is small, atanl(x)~=x */ + /* raise inexact */ + if (huge+x > one) + return x; + } + id = -1; + } else { + x = fabsl(x); + if (expman < (BIAS << 8) + 0x30) { /* |x| < 1.1875 */ + if (expman < ((BIAS - 1) << 8) + 0x60) { /* 7/16 <= |x| < 11/16 */ + id = 0; + x = (2.0*x-one)/(2.0+x); + } else { /* 11/16 <= |x| < 19/16 */ + id = 1; + x = (x-one)/(x+one); + } + } else { + if (expman < ((BIAS + 1) << 8) + 0x38) { /* |x| < 2.4375 */ + id = 2; + x = (x-1.5)/(one+1.5*x); + } else { /* 2.4375 <= |x| < 2^ATAN_CONST */ + id = 3; + x = -1.0/x; + } + } + } + /* end of argument reduction */ + z = x*x; + w = z*z; + /* break sum aT[i]z**(i+1) into odd and even poly */ + s1 = z*T_even(w); + s2 = w*T_odd(w); + if (id < 0) + return x - x*(s1+s2); + z = atanhi[id] - ((x*(s1+s2) - atanlo[id]) - x); + return expsign < 0 ? -z : z; +} +#endif |