mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-26 23:10:06 +00:00
117 lines
3.4 KiB
C
117 lines
3.4 KiB
C
/*
|
|
* IBM Accurate Mathematical Library
|
|
* written by International Business Machines Corp.
|
|
* Copyright (C) 2001-2017 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:mpatan.c */
|
|
/* */
|
|
/* FUNCTIONS:mpatan */
|
|
/* */
|
|
/* FILES NEEDED: mpa.h endian.h mpatan.h */
|
|
/* mpa.c */
|
|
/* */
|
|
/* Multi-Precision Atan function subroutine, for precision p >= 4.*/
|
|
/* The relative error of the result is bounded by 34.32*r**(1-p), */
|
|
/* where r=2**24. */
|
|
/******************************************************************/
|
|
|
|
#include "endian.h"
|
|
#include "mpa.h"
|
|
#include <math.h>
|
|
|
|
#ifndef SECTION
|
|
# define SECTION
|
|
#endif
|
|
|
|
#include "mpatan.h"
|
|
|
|
void
|
|
SECTION
|
|
__mpatan (mp_no *x, mp_no *y, int p)
|
|
{
|
|
int i, m, n;
|
|
double dx;
|
|
mp_no mptwoim1 =
|
|
{
|
|
0,
|
|
{
|
|
0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
|
|
0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
|
|
0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
|
|
}
|
|
};
|
|
|
|
mp_no mps, mpsm, mpt, mpt1, mpt2, mpt3;
|
|
|
|
/* Choose m and initiate mptwoim1. */
|
|
if (EX > 0)
|
|
m = 7;
|
|
else if (EX < 0)
|
|
m = 0;
|
|
else
|
|
{
|
|
__mp_dbl (x, &dx, p);
|
|
dx = fabs (dx);
|
|
for (m = 6; m > 0; m--)
|
|
{
|
|
if (dx > __atan_xm[m].d)
|
|
break;
|
|
}
|
|
}
|
|
mptwoim1.e = 1;
|
|
mptwoim1.d[0] = 1;
|
|
|
|
/* Reduce x m times. */
|
|
__sqr (x, &mpsm, p);
|
|
if (m == 0)
|
|
__cpy (x, &mps, p);
|
|
else
|
|
{
|
|
for (i = 0; i < m; i++)
|
|
{
|
|
__add (&__mpone, &mpsm, &mpt1, p);
|
|
__mpsqrt (&mpt1, &mpt2, p);
|
|
__add (&mpt2, &mpt2, &mpt1, p);
|
|
__add (&__mptwo, &mpsm, &mpt2, p);
|
|
__add (&mpt1, &mpt2, &mpt3, p);
|
|
__dvd (&mpsm, &mpt3, &mpt1, p);
|
|
__cpy (&mpt1, &mpsm, p);
|
|
}
|
|
__mpsqrt (&mpsm, &mps, p);
|
|
mps.d[0] = X[0];
|
|
}
|
|
|
|
/* Evaluate a truncated power series for Atan(s). */
|
|
n = __atan_np[p];
|
|
mptwoim1.d[1] = __atan_twonm1[p].d;
|
|
__dvd (&mpsm, &mptwoim1, &mpt, p);
|
|
for (i = n - 1; i > 1; i--)
|
|
{
|
|
mptwoim1.d[1] -= 2;
|
|
__dvd (&mpsm, &mptwoim1, &mpt1, p);
|
|
__mul (&mpsm, &mpt, &mpt2, p);
|
|
__sub (&mpt1, &mpt2, &mpt, p);
|
|
}
|
|
__mul (&mps, &mpt, &mpt1, p);
|
|
__sub (&mps, &mpt1, &mpt, p);
|
|
|
|
/* Compute Atan(x). */
|
|
mptwoim1.d[1] = 1 << m;
|
|
__mul (&mptwoim1, &mpt, y, p);
|
|
}
|