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Diffstat (limited to 'REORG.TODO/sysdeps/ieee754/ldbl-128/s_tanl.c')
| -rw-r--r-- | REORG.TODO/sysdeps/ieee754/ldbl-128/s_tanl.c | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/ieee754/ldbl-128/s_tanl.c b/REORG.TODO/sysdeps/ieee754/ldbl-128/s_tanl.c new file mode 100644 index 0000000000..cd7b258616 --- /dev/null +++ b/REORG.TODO/sysdeps/ieee754/ldbl-128/s_tanl.c @@ -0,0 +1,80 @@ +/* s_tanl.c -- long double version of s_tan.c. + * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz. + */ + +/* @(#)s_tan.c 5.1 93/09/24 */ +/* + * ==================================================== + * 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. + * ==================================================== + */ + +/* tanl(x) + * Return tangent function of x. + * + * kernel function: + * __kernel_tanl ... tangent function on [-pi/4,pi/4] + * __ieee754_rem_pio2l ... argument reduction routine + * + * Method. + * Let S,C and T denote the sin, cos and tan respectively on + * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2 + * in [-pi/4 , +pi/4], and let n = k mod 4. + * We have + * + * n sin(x) cos(x) tan(x) + * ---------------------------------------------------------- + * 0 S C T + * 1 C -S -1/T + * 2 -S -C T + * 3 -C S -1/T + * ---------------------------------------------------------- + * + * Special cases: + * Let trig be any of sin, cos, or tan. + * trig(+-INF) is NaN, with signals; + * trig(NaN) is that NaN; + * + * Accuracy: + * TRIG(x) returns trig(x) nearly rounded + */ + +#include <errno.h> +#include <math.h> +#include <math_private.h> + +_Float128 __tanl(_Float128 x) +{ + _Float128 y[2],z=0; + int64_t n, ix; + + /* High word of x. */ + GET_LDOUBLE_MSW64(ix,x); + + /* |x| ~< pi/4 */ + ix &= 0x7fffffffffffffffLL; + if(ix <= 0x3ffe921fb54442d1LL) return __kernel_tanl(x,z,1); + + /* tanl(Inf or NaN) is NaN */ + else if (ix>=0x7fff000000000000LL) { + if (ix == 0x7fff000000000000LL) { + GET_LDOUBLE_LSW64(n,x); + if (n == 0) + __set_errno (EDOM); + } + return x-x; /* NaN */ + } + + /* argument reduction needed */ + else { + n = __ieee754_rem_pio2l(x,y); + return __kernel_tanl(y[0],y[1],1-((n&1)<<1)); /* 1 -- n even + -1 -- n odd */ + } +} +weak_alias (__tanl, tanl) |