diff options
Diffstat (limited to 'libc-top-half/musl/src/math/atanl.c')
| -rw-r--r-- | libc-top-half/musl/src/math/atanl.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/libc-top-half/musl/src/math/atanl.c b/libc-top-half/musl/src/math/atanl.c new file mode 100644 index 0000000..c3b0c92 --- /dev/null +++ b/libc-top-half/musl/src/math/atanl.c @@ -0,0 +1,184 @@ +/* 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 + +#if LDBL_MANT_DIG == 64 +#define EXPMAN(u) ((u.i.se & 0x7fff)<<8 | (u.i.m>>55 & 0xff)) + +static const long double atanhi[] = { + 4.63647609000806116202e-01L, + 7.85398163397448309628e-01L, + 9.82793723247329067960e-01L, + 1.57079632679489661926e+00L, +}; + +static const long double atanlo[] = { + 1.18469937025062860669e-20L, + -1.25413940316708300586e-20L, + 2.55232234165405176172e-20L, + -2.50827880633416601173e-20L, +}; + +static const long double aT[] = { + 3.33333333333333333017e-01L, + -1.99999999999999632011e-01L, + 1.42857142857046531280e-01L, + -1.11111111100562372733e-01L, + 9.09090902935647302252e-02L, + -7.69230552476207730353e-02L, + 6.66661718042406260546e-02L, + -5.88158892835030888692e-02L, + 5.25499891539726639379e-02L, + -4.70119845393155721494e-02L, + 4.03539201366454414072e-02L, + -2.91303858419364158725e-02L, + 1.24822046299269234080e-02L, +}; + +static long double T_even(long double x) +{ + return aT[0] + x * (aT[2] + x * (aT[4] + x * (aT[6] + + x * (aT[8] + x * (aT[10] + x * aT[12]))))); +} + +static long double T_odd(long double x) +{ + return aT[1] + x * (aT[3] + x * (aT[5] + x * (aT[7] + + x * (aT[9] + x * aT[11])))); +} +#elif LDBL_MANT_DIG == 113 +#define EXPMAN(u) ((u.i.se & 0x7fff)<<8 | u.i.top>>8) + +static const long double atanhi[] = { + 4.63647609000806116214256231461214397e-01L, + 7.85398163397448309615660845819875699e-01L, + 9.82793723247329067985710611014666038e-01L, + 1.57079632679489661923132169163975140e+00L, +}; + +static const long double atanlo[] = { + 4.89509642257333492668618435220297706e-36L, + 2.16795253253094525619926100651083806e-35L, + -2.31288434538183565909319952098066272e-35L, + 4.33590506506189051239852201302167613e-35L, +}; + +static const long double aT[] = { + 3.33333333333333333333333333333333125e-01L, + -1.99999999999999999999999999999180430e-01L, + 1.42857142857142857142857142125269827e-01L, + -1.11111111111111111111110834490810169e-01L, + 9.09090909090909090908522355708623681e-02L, + -7.69230769230769230696553844935357021e-02L, + 6.66666666666666660390096773046256096e-02L, + -5.88235294117646671706582985209643694e-02L, + 5.26315789473666478515847092020327506e-02L, + -4.76190476189855517021024424991436144e-02L, + 4.34782608678695085948531993458097026e-02L, + -3.99999999632663469330634215991142368e-02L, + 3.70370363987423702891250829918659723e-02L, + -3.44827496515048090726669907612335954e-02L, + 3.22579620681420149871973710852268528e-02L, + -3.03020767654269261041647570626778067e-02L, + 2.85641979882534783223403715930946138e-02L, + -2.69824879726738568189929461383741323e-02L, + 2.54194698498808542954187110873675769e-02L, + -2.35083879708189059926183138130183215e-02L, + 2.04832358998165364349957325067131428e-02L, + -1.54489555488544397858507248612362957e-02L, + 8.64492360989278761493037861575248038e-03L, + -2.58521121597609872727919154569765469e-03L, +}; + +static long double T_even(long double x) +{ + return (aT[0] + x * (aT[2] + x * (aT[4] + x * (aT[6] + x * (aT[8] + + x * (aT[10] + x * (aT[12] + x * (aT[14] + x * (aT[16] + + x * (aT[18] + x * (aT[20] + x * aT[22]))))))))))); +} + +static long double T_odd(long double x) +{ + return (aT[1] + x * (aT[3] + x * (aT[5] + x * (aT[7] + x * (aT[9] + + x * (aT[11] + x * (aT[13] + x * (aT[15] + x * (aT[17] + + x * (aT[19] + x * (aT[21] + x * aT[23]))))))))))); +} +#endif + +long double atanl(long double x) +{ + union ldshape u = {x}; + long double w, s1, s2, z; + int id; + unsigned e = u.i.se & 0x7fff; + unsigned sign = u.i.se >> 15; + unsigned expman; + + if (e >= 0x3fff + LDBL_MANT_DIG + 1) { /* if |x| is large, atan(x)~=pi/2 */ + if (isnan(x)) + return x; + return sign ? -atanhi[3] : atanhi[3]; + } + /* Extract the exponent and the first few bits of the mantissa. */ + expman = EXPMAN(u); + if (expman < ((0x3fff - 2) << 8) + 0xc0) { /* |x| < 0.4375 */ + if (e < 0x3fff - (LDBL_MANT_DIG+1)/2) { /* if |x| is small, atanl(x)~=x */ + /* raise underflow if subnormal */ + if (e == 0) + FORCE_EVAL((float)x); + return x; + } + id = -1; + } else { + x = fabsl(x); + if (expman < (0x3fff << 8) + 0x30) { /* |x| < 1.1875 */ + if (expman < ((0x3fff - 1) << 8) + 0x60) { /* 7/16 <= |x| < 11/16 */ + id = 0; + x = (2.0*x-1.0)/(2.0+x); + } else { /* 11/16 <= |x| < 19/16 */ + id = 1; + x = (x-1.0)/(x+1.0); + } + } else { + if (expman < ((0x3fff + 1) << 8) + 0x38) { /* |x| < 2.4375 */ + id = 2; + x = (x-1.5)/(1.0+1.5*x); + } else { /* 2.4375 <= |x| */ + 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 sign ? -z : z; +} +#endif |