mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-27 21:20:18 +00:00
64 lines
2.5 KiB
C
64 lines
2.5 KiB
C
/*
|
|
* IBM Accurate Mathematical Library
|
|
* written by International Business Machines Corp.
|
|
* Copyright (C) 2001-2014 Free Software Foundation, Inc.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU Lesser General Public License as published by
|
|
* the Free Software Foundation; either version 2.1 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public License
|
|
* along with this program; if not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
/**********************************************************************/
|
|
/* MODULE_NAME:mptan.c */
|
|
/* */
|
|
/* FUNCTION: mptan */
|
|
/* */
|
|
/* FILES NEEDED: endian.h mpa.h */
|
|
/* mpa.c sincos32.c branred.c */
|
|
/* */
|
|
/* Multi-Precision tan() function subroutine, for p=32. It is based */
|
|
/* on the routines mpranred() and c32(). mpranred() performs range */
|
|
/* reduction of a double number x into a multiple precision number */
|
|
/* y, such that y=x-n*pi/2, abs(y)<pi/4, n=0,+-1,+-2,.... c32() */
|
|
/* computes both sin(y), cos(y). tan(x) is either sin(y)/cos(y) */
|
|
/* or -cos(y)/sin(y). The precision of the result is of about 559 */
|
|
/* significant bits. */
|
|
/* */
|
|
/**********************************************************************/
|
|
#include "endian.h"
|
|
#include "mpa.h"
|
|
|
|
#ifndef SECTION
|
|
# define SECTION
|
|
#endif
|
|
|
|
void
|
|
SECTION
|
|
__mptan (double x, mp_no *mpy, int p)
|
|
{
|
|
int n;
|
|
mp_no mpw, mpc, mps;
|
|
|
|
/* Negative or positive result. */
|
|
n = __mpranred (x, &mpw, p) & 0x00000001;
|
|
/* Computing sin(x) and cos(x). */
|
|
__c32 (&mpw, &mpc, &mps, p);
|
|
/* Second or fourth quarter of unit circle. */
|
|
if (n)
|
|
{
|
|
__dvd (&mpc, &mps, mpy, p);
|
|
mpy->d[0] *= -1;
|
|
}
|
|
/* tan is negative in this area. */
|
|
else
|
|
__dvd (&mps, &mpc, mpy, p);
|
|
}
|