/* origin: FreeBSD /usr/src/lib/msun/src/s_tanl.c */
/*-
* Copyright (c) 2007 Steven G. Kargl
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice unmodified, this list of conditions, and the following
* disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Limited testing on pseudorandom numbers drawn within [0:4e8] shows
* an accuracy of <= 1.5 ULP where 247024 values of x out of 40 million
* possibles resulted in tan(x) that exceeded 0.5 ULP (ie., 0.6%).
*/
#include "libm.h"
#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
long double tanl(long double x)
{
return tan(x);
}
#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
long double tanl(long double x)
{
union IEEEl2bits z;
int e0, s;
long double y[2];
long double hi, lo;
z.e = x;
s = z.bits.sign;
z.bits.sign = 0;
/* If x = +-0 or x is subnormal, then tan(x) = x. */
if (z.bits.exp == 0)
return x;
/* If x = NaN or Inf, then tan(x) = NaN. */
if (z.bits.exp == 32767)
return (x - x) / (x - x);
/* Optimize the case where x is already within range. */
if (z.e < M_PI_4) {
hi = __tanl(z.e, 0, 0);
return s ? -hi : hi;
}
e0 = __rem_pio2l(x, y);
hi = y[0];
lo = y[1];
switch (e0 & 3) {
case 0:
case 2:
hi = __tanl(hi, lo, 0);
break;
case 1:
case 3:
hi = __tanl(hi, lo, 1);
break;
}
return hi;
}
#endif
