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/* origin: FreeBSD /usr/src/lib/msun/src/s_tanf.c */
/*
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
* Optimized by Bruce D. Evans.
*/
/*
* ====================================================
* 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.
* ====================================================
*/
#include "libm.h"
/* Small multiples of pi/2 rounded to double precision. */
static const double
t1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */
t2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */
t3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */
t4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */
float tanf(float x)
{
double y;
int32_t n, hx, ix;
GET_FLOAT_WORD(hx, x);
ix = hx & 0x7fffffff;
if (ix <= 0x3f490fda) { /* |x| ~<= pi/4 */
if (ix < 0x39800000) /* |x| < 2**-12 */
/* return x and raise inexact if x != 0 */
if ((int)x == 0)
return x;
return __tandf(x, 1);
}
if (ix <= 0x407b53d1) { /* |x| ~<= 5*pi/4 */
if (ix <= 0x4016cbe3) /* |x| ~<= 3pi/4 */
return __tandf((hx > 0 ? x-t1pio2 : x+t1pio2), -1);
else
return __tandf((hx > 0 ? x-t2pio2 : x+t2pio2), 1);
}
if (ix <= 0x40e231d5) { /* |x| ~<= 9*pi/4 */
if (ix <= 0x40afeddf) /* |x| ~<= 7*pi/4 */
return __tandf((hx > 0 ? x-t3pio2 : x+t3pio2), -1);
else
return __tandf((hx > 0 ? x-t4pio2 : x+t4pio2), 1);
}
/* tan(Inf or NaN) is NaN */
if (ix >= 0x7f800000)
return x - x;
/* general argument reduction needed */
n = __rem_pio2f(x, &y);
/* integer parameter: n even: 1; n odd: -1 */
return __tandf(y, 1-((n&1)<<1));
}
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