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| author | Roland McGrath <roland@gnu.org> | 1996-03-05 21:41:30 +0000 |
|---|---|---|
| committer | Roland McGrath <roland@gnu.org> | 1996-03-05 21:41:30 +0000 |
| commit | f7eac6eb504f4baf13dbb4d26717942df050ebe6 (patch) | |
| tree | 95ff129c06c7f6f246a5e2bfa489ba6382659d19 /sysdeps/libm-ieee754/s_tan.c | |
| parent | 1521668f2afae1dc2ef5d7ffaeb84353b36874dd (diff) | |
| download | glibc-f7eac6eb504f4baf13dbb4d26717942df050ebe6.zip glibc-f7eac6eb504f4baf13dbb4d26717942df050ebe6.tar.gz glibc-f7eac6eb504f4baf13dbb4d26717942df050ebe6.tar.bz2 | |
Mon Mar 4 20:54:40 1996 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* Makeconfig ($(common-objpfx)config.make): Depend on config.h.in.
Mon Mar 4 17:35:09 1996 Roland McGrath <roland@charlie-brown.gnu.ai.mit.edu>
* hurd/catch-signal.c (hurd_safe_memmove): New function.
(hurd_safe_copyin, hurd_safe_copyout): New functions.
* hurd/hurd/sigpreempt.h: Declare them.
Sun Mar 3 08:43:44 1996 Roland McGrath <roland@charlie-brown.gnu.ai.mit.edu>
Replace math code with fdlibm from Sun as modified for netbsd by
JT Conklin and Ian Taylor, including x86 FPU support.
* sysdeps/libm-ieee754, sysdeps/libm-i387: New directories.
* math/math_private.h: New file.
* sysdeps/i386/fpu/Implies: New file.
* sysdeps/ieee754/Implies: New file.
* math/machine/asm.h, math/machine/endian.h: New files.
* math/Makefile, math/math.h: Rewritten.
* mathcalls.h, math/mathcalls.h: New file, broken out of math.h.
* math/finite.c: File removed.
* sysdeps/generic/Makefile [$(subdir)=math]: Frobnication removed.
* math/test-math.c: Include errno.h and string.h.
* sysdeps/unix/bsd/dirstream.h: File removed.
* sysdeps/unix/bsd/readdir.c: File removed.
Diffstat (limited to 'sysdeps/libm-ieee754/s_tan.c')
| -rw-r--r-- | sysdeps/libm-ieee754/s_tan.c | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/sysdeps/libm-ieee754/s_tan.c b/sysdeps/libm-ieee754/s_tan.c new file mode 100644 index 0000000..dcd9d50 --- /dev/null +++ b/sysdeps/libm-ieee754/s_tan.c @@ -0,0 +1,77 @@ +/* @(#)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. + * ==================================================== + */ + +#if defined(LIBM_SCCS) && !defined(lint) +static char rcsid[] = "$NetBSD: s_tan.c,v 1.7 1995/05/10 20:48:18 jtc Exp $"; +#endif + +/* tan(x) + * Return tangent function of x. + * + * kernel function: + * __kernel_tan ... tangent function on [-pi/4,pi/4] + * __ieee754_rem_pio2 ... 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 "math.h" +#include "math_private.h" + +#ifdef __STDC__ + double __tan(double x) +#else + double __tan(x) + double x; +#endif +{ + double y[2],z=0.0; + int32_t n, ix; + + /* High word of x. */ + GET_HIGH_WORD(ix,x); + + /* |x| ~< pi/4 */ + ix &= 0x7fffffff; + if(ix <= 0x3fe921fb) return __kernel_tan(x,z,1); + + /* tan(Inf or NaN) is NaN */ + else if (ix>=0x7ff00000) return x-x; /* NaN */ + + /* argument reduction needed */ + else { + n = __ieee754_rem_pio2(x,y); + return __kernel_tan(y[0],y[1],1-((n&1)<<1)); /* 1 -- n even + -1 -- n odd */ + } +} +weak_alias (__tan, tan) |