2012-03-13 01:17:53 -04:00
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/* origin: FreeBSD /usr/src/lib/msun/src/s_tanl.c */
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2011-02-12 00:22:29 -05:00
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/*-
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2012-03-13 01:17:53 -04:00
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* Copyright (c) 2007 Steven G. Kargl
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2011-02-12 00:22:29 -05:00
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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2012-03-13 01:17:53 -04:00
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/*
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* Limited testing on pseudorandom numbers drawn within [0:4e8] shows
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* an accuracy of <= 1.5 ULP where 247024 values of x out of 40 million
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* possibles resulted in tan(x) that exceeded 0.5 ULP (ie., 0.6%).
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*/
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#include "libm.h"
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2011-02-12 00:22:29 -05:00
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2012-03-13 01:17:53 -04:00
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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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long double tanl(long double x)
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{
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return tan(x);
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}
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#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
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long double tanl(long double x)
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{
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2012-03-13 01:17:53 -04:00
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union IEEEl2bits z;
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long double y[2];
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2013-05-18 12:34:00 +00:00
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unsigned n;
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2012-03-13 01:17:53 -04:00
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z.e = x;
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z.bits.sign = 0;
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/* If x = NaN or Inf, then tan(x) = NaN. */
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2013-05-18 12:34:00 +00:00
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if (z.bits.exp == 0x7fff)
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2012-03-13 01:17:53 -04:00
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return (x - x) / (x - x);
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2013-05-18 12:34:00 +00:00
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/* |x| < (double)pi/4 */
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2012-03-13 01:17:53 -04:00
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if (z.e < M_PI_4) {
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2013-05-18 12:34:00 +00:00
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/* x = +-0 or x is subnormal */
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if (z.bits.exp == 0)
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/* inexact and underflow if x!=0 */
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return x + x*0x1p-120f;
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/* can raise spurious underflow */
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return __tanl(x, 0, 0);
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2012-03-13 01:17:53 -04:00
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}
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2013-05-18 12:34:00 +00:00
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n = __rem_pio2l(x, y);
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return __tanl(y[0], y[1], n&1);
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2011-02-12 00:22:29 -05:00
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}
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2012-03-13 01:17:53 -04:00
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#endif
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