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authorRoland McGrath <roland@gnu.org>1996-03-05 21:41:30 +0000
committerRoland McGrath <roland@gnu.org>1996-03-05 21:41:30 +0000
commitf7eac6eb504f4baf13dbb4d26717942df050ebe6 (patch)
tree95ff129c06c7f6f246a5e2bfa489ba6382659d19 /sysdeps/libm-ieee754/e_atan2.c
parent1521668f2afae1dc2ef5d7ffaeb84353b36874dd (diff)
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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/e_atan2.c')
-rw-r--r--sysdeps/libm-ieee754/e_atan2.c130
1 files changed, 130 insertions, 0 deletions
diff --git a/sysdeps/libm-ieee754/e_atan2.c b/sysdeps/libm-ieee754/e_atan2.c
new file mode 100644
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+++ b/sysdeps/libm-ieee754/e_atan2.c
@@ -0,0 +1,130 @@
+/* @(#)e_atan2.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: e_atan2.c,v 1.8 1995/05/10 20:44:51 jtc Exp $";
+#endif
+
+/* __ieee754_atan2(y,x)
+ * Method :
+ *	1. Reduce y to positive by atan2(y,x)=-atan2(-y,x).
+ *	2. Reduce x to positive by (if x and y are unexceptional): 
+ *		ARG (x+iy) = arctan(y/x)   	   ... if x > 0,
+ *		ARG (x+iy) = pi - arctan[y/(-x)]   ... if x < 0,
+ *
+ * Special cases:
+ *
+ *	ATAN2((anything), NaN ) is NaN;
+ *	ATAN2(NAN , (anything) ) is NaN;
+ *	ATAN2(+-0, +(anything but NaN)) is +-0  ;
+ *	ATAN2(+-0, -(anything but NaN)) is +-pi ;
+ *	ATAN2(+-(anything but 0 and NaN), 0) is +-pi/2;
+ *	ATAN2(+-(anything but INF and NaN), +INF) is +-0 ;
+ *	ATAN2(+-(anything but INF and NaN), -INF) is +-pi;
+ *	ATAN2(+-INF,+INF ) is +-pi/4 ;
+ *	ATAN2(+-INF,-INF ) is +-3pi/4;
+ *	ATAN2(+-INF, (anything but,0,NaN, and INF)) is +-pi/2;
+ *
+ * Constants:
+ * The hexadecimal values are the intended ones for the following 
+ * constants. The decimal values may be used, provided that the 
+ * compiler will convert from decimal to binary accurately enough 
+ * to produce the hexadecimal values shown.
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const double 
+#else
+static double 
+#endif
+tiny  = 1.0e-300,
+zero  = 0.0,
+pi_o_4  = 7.8539816339744827900E-01, /* 0x3FE921FB, 0x54442D18 */
+pi_o_2  = 1.5707963267948965580E+00, /* 0x3FF921FB, 0x54442D18 */
+pi      = 3.1415926535897931160E+00, /* 0x400921FB, 0x54442D18 */
+pi_lo   = 1.2246467991473531772E-16; /* 0x3CA1A626, 0x33145C07 */
+
+#ifdef __STDC__
+	double __ieee754_atan2(double y, double x)
+#else
+	double __ieee754_atan2(y,x)
+	double  y,x;
+#endif
+{  
+	double z;
+	int32_t k,m,hx,hy,ix,iy;
+	u_int32_t lx,ly;
+
+	EXTRACT_WORDS(hx,lx,x);
+	ix = hx&0x7fffffff;
+	EXTRACT_WORDS(hy,ly,y);
+	iy = hy&0x7fffffff;
+	if(((ix|((lx|-lx)>>31))>0x7ff00000)||
+	   ((iy|((ly|-ly)>>31))>0x7ff00000))	/* x or y is NaN */
+	   return x+y;
+	if((hx-0x3ff00000|lx)==0) return atan(y);   /* x=1.0 */
+	m = ((hy>>31)&1)|((hx>>30)&2);	/* 2*sign(x)+sign(y) */
+
+    /* when y = 0 */
+	if((iy|ly)==0) {
+	    switch(m) {
+		case 0: 
+		case 1: return y; 	/* atan(+-0,+anything)=+-0 */
+		case 2: return  pi+tiny;/* atan(+0,-anything) = pi */
+		case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */
+	    }
+	}
+    /* when x = 0 */
+	if((ix|lx)==0) return (hy<0)?  -pi_o_2-tiny: pi_o_2+tiny;
+	    
+    /* when x is INF */
+	if(ix==0x7ff00000) {
+	    if(iy==0x7ff00000) {
+		switch(m) {
+		    case 0: return  pi_o_4+tiny;/* atan(+INF,+INF) */
+		    case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */
+		    case 2: return  3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/
+		    case 3: return -3.0*pi_o_4-tiny;/*atan(-INF,-INF)*/
+		}
+	    } else {
+		switch(m) {
+		    case 0: return  zero  ;	/* atan(+...,+INF) */
+		    case 1: return -zero  ;	/* atan(-...,+INF) */
+		    case 2: return  pi+tiny  ;	/* atan(+...,-INF) */
+		    case 3: return -pi-tiny  ;	/* atan(-...,-INF) */
+		}
+	    }
+	}
+    /* when y is INF */
+	if(iy==0x7ff00000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;
+
+    /* compute y/x */
+	k = (iy-ix)>>20;
+	if(k > 60) z=pi_o_2+0.5*pi_lo; 	/* |y/x| >  2**60 */
+	else if(hx<0&&k<-60) z=0.0; 	/* |y|/x < -2**60 */
+	else z=atan(fabs(y/x));		/* safe to do y/x */
+	switch (m) {
+	    case 0: return       z  ;	/* atan(+,+) */
+	    case 1: {
+	    	      u_int32_t zh;
+		      GET_HIGH_WORD(zh,z);
+		      SET_HIGH_WORD(z,zh ^ 0x80000000);
+		    }
+		    return       z  ;	/* atan(-,+) */
+	    case 2: return  pi-(z-pi_lo);/* atan(+,-) */
+	    default: /* case 3 */
+	    	    return  (z-pi_lo)-pi;/* atan(-,-) */
+	}
+}