125c28e83SPiotr Jasiukajtis /*
225c28e83SPiotr Jasiukajtis * CDDL HEADER START
325c28e83SPiotr Jasiukajtis *
425c28e83SPiotr Jasiukajtis * The contents of this file are subject to the terms of the
525c28e83SPiotr Jasiukajtis * Common Development and Distribution License (the "License").
625c28e83SPiotr Jasiukajtis * You may not use this file except in compliance with the License.
725c28e83SPiotr Jasiukajtis *
825c28e83SPiotr Jasiukajtis * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
925c28e83SPiotr Jasiukajtis * or http://www.opensolaris.org/os/licensing.
1025c28e83SPiotr Jasiukajtis * See the License for the specific language governing permissions
1125c28e83SPiotr Jasiukajtis * and limitations under the License.
1225c28e83SPiotr Jasiukajtis *
1325c28e83SPiotr Jasiukajtis * When distributing Covered Code, include this CDDL HEADER in each
1425c28e83SPiotr Jasiukajtis * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
1525c28e83SPiotr Jasiukajtis * If applicable, add the following below this CDDL HEADER, with the
1625c28e83SPiotr Jasiukajtis * fields enclosed by brackets "[]" replaced with your own identifying
1725c28e83SPiotr Jasiukajtis * information: Portions Copyright [yyyy] [name of copyright owner]
1825c28e83SPiotr Jasiukajtis *
1925c28e83SPiotr Jasiukajtis * CDDL HEADER END
2025c28e83SPiotr Jasiukajtis */
2125c28e83SPiotr Jasiukajtis
2225c28e83SPiotr Jasiukajtis /*
2325c28e83SPiotr Jasiukajtis * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
2425c28e83SPiotr Jasiukajtis */
2525c28e83SPiotr Jasiukajtis /*
2625c28e83SPiotr Jasiukajtis * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
2725c28e83SPiotr Jasiukajtis * Use is subject to license terms.
2825c28e83SPiotr Jasiukajtis */
2925c28e83SPiotr Jasiukajtis
30*ddc0e0b5SRichard Lowe #pragma weak __cbrtl = cbrtl
3125c28e83SPiotr Jasiukajtis
3225c28e83SPiotr Jasiukajtis #include "libm.h"
3325c28e83SPiotr Jasiukajtis #include "longdouble.h"
3425c28e83SPiotr Jasiukajtis
3525c28e83SPiotr Jasiukajtis static const double d_one = 1.0;
3625c28e83SPiotr Jasiukajtis
3725c28e83SPiotr Jasiukajtis long double
cbrtl(long double x)3825c28e83SPiotr Jasiukajtis cbrtl(long double x) {
3925c28e83SPiotr Jasiukajtis long double s, t, r, w, y;
4025c28e83SPiotr Jasiukajtis double dx, dy;
4125c28e83SPiotr Jasiukajtis int *py = (int *) &dy;
4225c28e83SPiotr Jasiukajtis int n, m, m3, n0, sx;
4325c28e83SPiotr Jasiukajtis
4425c28e83SPiotr Jasiukajtis if (!finitel(x))
4525c28e83SPiotr Jasiukajtis return (x + x);
4625c28e83SPiotr Jasiukajtis if (iszerol(x))
4725c28e83SPiotr Jasiukajtis return (x);
4825c28e83SPiotr Jasiukajtis n0 = 0;
4925c28e83SPiotr Jasiukajtis if (*((int *) &d_one) == 0)
5025c28e83SPiotr Jasiukajtis n0 = 1;
5125c28e83SPiotr Jasiukajtis sx = signbitl(x);
5225c28e83SPiotr Jasiukajtis x = fabsl(x);
5325c28e83SPiotr Jasiukajtis n = ilogbl(x);
5425c28e83SPiotr Jasiukajtis m = n / 3;
5525c28e83SPiotr Jasiukajtis m3 = m + m + m;
5625c28e83SPiotr Jasiukajtis y = scalbnl(x, -m3);
5725c28e83SPiotr Jasiukajtis dx = (double) y;
5825c28e83SPiotr Jasiukajtis dy = cbrt(dx);
5925c28e83SPiotr Jasiukajtis py[1 - n0] += 2;
6025c28e83SPiotr Jasiukajtis if (py[1 - n0] == 0)
6125c28e83SPiotr Jasiukajtis py[n0] += 1;
6225c28e83SPiotr Jasiukajtis
6325c28e83SPiotr Jasiukajtis /* one step newton iteration to 113 bits with error < 0.667ulps */
6425c28e83SPiotr Jasiukajtis t = (long double) dy;
6525c28e83SPiotr Jasiukajtis t = scalbnl(t, m);
6625c28e83SPiotr Jasiukajtis s = t * t;
6725c28e83SPiotr Jasiukajtis r = x / s;
6825c28e83SPiotr Jasiukajtis w = t + t;
6925c28e83SPiotr Jasiukajtis r = (r - t) / (w + r);
7025c28e83SPiotr Jasiukajtis t += t * r;
7125c28e83SPiotr Jasiukajtis
7225c28e83SPiotr Jasiukajtis return (sx == 0 ? t : -t);
7325c28e83SPiotr Jasiukajtis }
74