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Merge a bugfix from FDLIBM 5.3 to ensure that the error in tan()

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is always less than 1 ulp.  Also update to the 5.3 license.

Obtained from:	FDLIBM
This commit is contained in:
David Schultz 2004-06-02 04:39:29 +00:00
parent 2658b3bb8e
commit 21d39caaee
1 changed files with 24 additions and 10 deletions
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34
lib/msun/src/k_tan.c
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@ -1,9 +1,8 @@
/* @(#)k_tan.c 5.1 93/09/24 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
* Copyright 2004 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.
@ -77,14 +76,29 @@ __kernel_tan(double x, double y, int iy)
int32_t ix,hx;
GET_HIGH_WORD(hx,x);
ix = hx&0x7fffffff; /* high word of |x| */
if(ix<0x3e300000) /* x < 2**-28 */
{if((int)x==0) { /* generate inexact */
u_int32_t low;
GET_LOW_WORD(low,x);
if(((ix|low)|(iy+1))==0) return one/fabs(x);
else return (iy==1)? x: -one/x;
}
}
if(ix<0x3e300000) { /* x < 2**-28 */
if ((int) x == 0) { /* generate inexact */
u_int32_t low;
GET_LOW_WORD(low,x);
if (((ix | low) | (iy + 1)) == 0)
return one / fabs(x);
else {
if (iy == 1)
return x;
else { /* compute -1 / (x+y) carefully */
double a, t;
z = w = x + y;
SET_LOW_WORD(z, 0);
v = y - (z - x);
t = a = -one / w;
SET_LOW_WORD(t, 0);
s = one + t * z;
return t + a * (s + t * v);
}
}
}
}
if(ix>=0x3FE59428) { /* |x|>=0.6744 */
if(hx<0) {x = -x; y = -y;}
z = pio4-x;