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author | Szabolcs Nagy <nsz@port70.net> | 2013-09-03 15:02:10 +0000 |
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committer | Szabolcs Nagy <nsz@port70.net> | 2013-09-05 11:30:07 +0000 |
commit | bcd797a5ba4631c031919dad832d670e564212e9 (patch) | |
tree | 4ad873585d3e87dfca85b16baa3b6613a7e9f479 /src/math/acosl.c | |
parent | c2a0dfea629617a39af2f59bd400e1a3595d0783 (diff) | |
download | musl-bcd797a5ba4631c031919dad832d670e564212e9.tar.gz musl-bcd797a5ba4631c031919dad832d670e564212e9.tar.bz2 musl-bcd797a5ba4631c031919dad832d670e564212e9.tar.xz musl-bcd797a5ba4631c031919dad832d670e564212e9.zip |
math: long double inverse trigonometric cleanup (acosl, asinl, atanl, atan2l)
* added ld128 support from freebsd fdlibm (untested)
* using new ldshape union instead of IEEEl2bits
* inexact status flag is not supported
Diffstat (limited to 'src/math/acosl.c')
-rw-r--r-- | src/math/acosl.c | 57 |
1 files changed, 28 insertions, 29 deletions
diff --git a/src/math/acosl.c b/src/math/acosl.c index 9e7b7fb3..c03bdf02 100644 --- a/src/math/acosl.c +++ b/src/math/acosl.c @@ -23,46 +23,45 @@ long double acosl(long double x) } #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384 #include "__invtrigl.h" +#if LDBL_MANT_DIG == 64 +#define CLEARBOTTOM(u) (u.i.m &= -1ULL << 32) +#elif LDBL_MANT_DIG == 113 +#define CLEARBOTTOM(u) (u.i.lo = 0) +#endif long double acosl(long double x) { - union IEEEl2bits u; - long double z, w, s, c, df; - int16_t expsign, expt; - u.e = x; - expsign = u.xbits.expsign; - expt = expsign & 0x7fff; + union ldshape u = {x}; + long double z, s, c, f; + uint16_t e = u.i.se & 0x7fff; + /* |x| >= 1 or nan */ - if (expt >= 0x3fff) { - if (expt == 0x3fff && - ((u.bits.manh & ~LDBL_NBIT) | u.bits.manl) == 0) { - if (expsign > 0) - return 0; /* acos(1) = 0 */ - return 2*pio2_hi + 0x1p-120f; /* acos(-1)= pi */ - } - return 0/(x-x); /* acos(|x|>1) is NaN */ + if (e >= 0x3fff) { + if (x == 1) + return 0; + if (x == -1) + return 2*pio2_hi + 0x1p-120f; + return 0/(x-x); } /* |x| < 0.5 */ - if (expt < 0x3fff - 1) { - if (expt < 0x3fff - 65) - return pio2_hi + 0x1p-120f; /* x < 0x1p-65: acosl(x)=pi/2 */ - return pio2_hi - (x - (pio2_lo - x * __invtrigl_R(x*x))); + if (e < 0x3fff - 1) { + if (e < 0x3fff - LDBL_MANT_DIG - 1) + return pio2_hi + 0x1p-120f; + return pio2_hi - (__invtrigl_R(x*x)*x - pio2_lo + x); } /* x < -0.5 */ - if (expsign < 0) { - z = (1.0 + x) * 0.5; + if (u.i.se >> 15) { + z = (1 + x)*0.5; s = sqrtl(z); - w = __invtrigl_R(z) * s - pio2_lo; - return 2*(pio2_hi - (s + w)); + return 2*(pio2_hi - (__invtrigl_R(z)*s - pio2_lo + s)); } /* x > 0.5 */ - z = (1.0 - x) * 0.5; + z = (1 - x)*0.5; s = sqrtl(z); - u.e = s; - u.bits.manl = 0; - df = u.e; - c = (z - df * df) / (s + df); - w = __invtrigl_R(z) * s + c; - return 2*(df + w); + u.f = s; + CLEARBOTTOM(u); + f = u.f; + c = (z - f*f)/(s + f); + return 2*(__invtrigl_R(z)*s + c + f); } #endif |