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comparison libquadmath/math/atanq.c @ 145:1830386684a0

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gcc-9.2.0
author anatofuz
date Thu, 13 Feb 2020 11:34:05 +0900
parents 04ced10e8804
children
comparison
equal deleted inserted replaced
131:84e7813d76e9 145:1830386684a0
1 /* s_atanl.c 1 /* s_atanl.c
2 * 2 *
3 * Inverse circular tangent for 128-bit __float128 precision 3 * Inverse circular tangent for 128-bit long double precision
4 * (arctangent) 4 * (arctangent)
5 * 5 *
6 * 6 *
7 * 7 *
8 * SYNOPSIS: 8 * SYNOPSIS:
9 * 9 *
10 * __float128 x, y, atanl(); 10 * long double x, y, atanq();
11 * 11 *
12 * y = atanl( x ); 12 * y = atanq( x );
13 * 13 *
14 * 14 *
15 * 15 *
16 * DESCRIPTION: 16 * DESCRIPTION:
17 * 17 *
53 but WITHOUT ANY WARRANTY; without even the implied warranty of 53 but WITHOUT ANY WARRANTY; without even the implied warranty of
54 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 54 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
55 Lesser General Public License for more details. 55 Lesser General Public License for more details.
56 56
57 You should have received a copy of the GNU Lesser General Public 57 You should have received a copy of the GNU Lesser General Public
58 License along with this library; if not, write to the Free Software 58 License along with this library; if not, see
59 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ 59 <http://www.gnu.org/licenses/>. */
60
61 60
62 #include "quadmath-imp.h" 61 #include "quadmath-imp.h"
63 62
64 /* arctan(k/8), k = 0, ..., 82 */ 63 /* arctan(k/8), k = 0, ..., 82 */
65 static const __float128 atantbl[84] = { 64 static const __float128 atantbl[84] = {
226 else 225 else
227 { 226 {
228 /* Index of nearest table element. 227 /* Index of nearest table element.
229 Roundoff to integer is asymmetrical to avoid cancellation when t < 0 228 Roundoff to integer is asymmetrical to avoid cancellation when t < 0
230 (cf. fdlibm). */ 229 (cf. fdlibm). */
231 k = 8.0Q * x + 0.25Q; 230 k = 8.0 * x + 0.25;
232 u = 0.125Q * k; 231 u = 0.125Q * k;
233 /* Small arctan argument. */ 232 /* Small arctan argument. */
234 t = (x - u) / (1.0 + x * u); 233 t = (x - u) / (1.0 + x * u);
235 } 234 }
236 235