1 /* tancotf.c: Computes tan or cot of a 32-bit float as outlined in [1]
3 Copyright (C) 2001, 2002 Jesus Calvino-Fraga, jesusc@ieee.org
5 This library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 This library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with this library; if not, write to the Free Software
17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
19 /* [1] William James Cody and W. M. Waite. _Software manual for the
20 elementary functions_, Englewood Cliffs, N.J.:Prentice-Hall, 1980. */
22 /* Version 1.0 - Initial release */
27 #define P0 0.100000000E+1
28 #define P1 -0.958017723E-1
29 #define Q0 0.100000000E+1
30 #define Q1 -0.429135777E+0
31 #define Q2 0.971685835E-2
34 #define C2 4.83826794897E-4
36 #define P(f,g) (P1*g*f+f)
37 #define Q(g) ((Q2*g+Q1)*g+Q0)
39 //A reasonable choice for YMAX is the integer part of B**(t/2)*PI/2:
42 float tancotf(const float x, const int iscotan)
44 float f, g, xn, xnum, xden;
53 /*Round x*2*PI to the nearest integer*/
54 n=(x*TWO_O_PI+(x>0.0?0.5:-0.5)); /*works for +-x*/
59 f=((xnum-xn*C1)+xden)-xn*C2;
76 if(iscotan) return (-xnum/xden);
77 else return (-xden/xnum);
81 if(iscotan) return (xden/xnum);
82 else return (xnum/xden);