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37550cb3d6
Similar to various other bugs in this area, some tan implementations do not raise the underflow exception for subnormal arguments, when the result is tiny and inexact. This patch forces the exception in a similar way to previous fixes. Tested for x86_64, x86, mips64 and powerpc. [BZ #16517] * sysdeps/ieee754/dbl-64/s_tan.c: Include <float.h>. (tan): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/flt-32/k_tanf.c: Include <float.h>. (__kernel_tanf): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/ldbl-128/k_tanl.c: Include <float.h>. (__kernel_tanl): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/ldbl-128ibm/k_tanl.c: Include <float.h>. (__kernel_tanl): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/ldbl-96/k_tanl.c: Include <float.h>. (__kernel_tanl): Force underflow exception for arguments with small absolute value. * math/auto-libm-test-in: Add more tests of tan. * math/auto-libm-test-out: Regenerated.
106 lines
2.9 KiB
C
106 lines
2.9 KiB
C
/* k_tanf.c -- float version of k_tan.c
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: k_tanf.c,v 1.4 1995/05/10 20:46:39 jtc Exp $";
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#endif
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#include <float.h>
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#include <math.h>
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#include <math_private.h>
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static const float
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one = 1.0000000000e+00, /* 0x3f800000 */
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pio4 = 7.8539812565e-01, /* 0x3f490fda */
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pio4lo= 3.7748947079e-08, /* 0x33222168 */
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T[] = {
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3.3333334327e-01, /* 0x3eaaaaab */
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1.3333334029e-01, /* 0x3e088889 */
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5.3968254477e-02, /* 0x3d5d0dd1 */
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2.1869488060e-02, /* 0x3cb327a4 */
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8.8632395491e-03, /* 0x3c11371f */
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3.5920790397e-03, /* 0x3b6b6916 */
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1.4562094584e-03, /* 0x3abede48 */
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5.8804126456e-04, /* 0x3a1a26c8 */
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2.4646313977e-04, /* 0x398137b9 */
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7.8179444245e-05, /* 0x38a3f445 */
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7.1407252108e-05, /* 0x3895c07a */
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-1.8558637748e-05, /* 0xb79bae5f */
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2.5907305826e-05, /* 0x37d95384 */
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};
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float __kernel_tanf(float x, float y, int iy)
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{
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float z,r,v,w,s;
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int32_t ix,hx;
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GET_FLOAT_WORD(hx,x);
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ix = hx&0x7fffffff; /* high word of |x| */
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if(ix<0x39000000) /* x < 2**-13 */
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{if((int)x==0) { /* generate inexact */
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if((ix|(iy+1))==0) return one/fabsf(x);
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else if (iy == 1)
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{
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if (fabsf (x) < FLT_MIN)
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{
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float force_underflow = x * x;
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math_force_eval (force_underflow);
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}
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return x;
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}
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else
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return -one / x;
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}
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}
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if(ix>=0x3f2ca140) { /* |x|>=0.6744 */
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if(hx<0) {x = -x; y = -y;}
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z = pio4-x;
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w = pio4lo-y;
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x = z+w; y = 0.0;
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if (fabsf (x) < 0x1p-13f)
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return (1 - ((hx >> 30) & 2)) * iy * (1.0f - 2 * iy * x);
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}
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z = x*x;
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w = z*z;
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/* Break x^5*(T[1]+x^2*T[2]+...) into
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* x^5(T[1]+x^4*T[3]+...+x^20*T[11]) +
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* x^5(x^2*(T[2]+x^4*T[4]+...+x^22*[T12]))
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*/
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r = T[1]+w*(T[3]+w*(T[5]+w*(T[7]+w*(T[9]+w*T[11]))));
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v = z*(T[2]+w*(T[4]+w*(T[6]+w*(T[8]+w*(T[10]+w*T[12])))));
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s = z*x;
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r = y + z*(s*(r+v)+y);
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r += T[0]*s;
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w = x+r;
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if(ix>=0x3f2ca140) {
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v = (float)iy;
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return (float)(1-((hx>>30)&2))*(v-(float)2.0*(x-(w*w/(w+v)-r)));
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}
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if(iy==1) return w;
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else { /* if allow error up to 2 ulp,
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simply return -1.0/(x+r) here */
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/* compute -1.0/(x+r) accurately */
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float a,t;
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int32_t i;
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z = w;
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GET_FLOAT_WORD(i,z);
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SET_FLOAT_WORD(z,i&0xfffff000);
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v = r-(z - x); /* z+v = r+x */
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t = a = -(float)1.0/w; /* a = -1.0/w */
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GET_FLOAT_WORD(i,t);
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SET_FLOAT_WORD(t,i&0xfffff000);
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s = (float)1.0+t*z;
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return t+a*(s+t*v);
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}
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}
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