Line | Count | Source (jump to first uncovered line) |
1 | | /* mpz_root(root, u, nth) -- Set ROOT to floor(U^(1/nth)). |
2 | | Return an indication if the result is exact. |
3 | | |
4 | | Copyright 1999-2003, 2005, 2012, 2020 Free Software Foundation, Inc. |
5 | | |
6 | | This file is part of the GNU MP Library. |
7 | | |
8 | | The GNU MP Library is free software; you can redistribute it and/or modify |
9 | | it under the terms of either: |
10 | | |
11 | | * the GNU Lesser General Public License as published by the Free |
12 | | Software Foundation; either version 3 of the License, or (at your |
13 | | option) any later version. |
14 | | |
15 | | or |
16 | | |
17 | | * the GNU General Public License as published by the Free Software |
18 | | Foundation; either version 2 of the License, or (at your option) any |
19 | | later version. |
20 | | |
21 | | or both in parallel, as here. |
22 | | |
23 | | The GNU MP Library is distributed in the hope that it will be useful, but |
24 | | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
25 | | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
26 | | for more details. |
27 | | |
28 | | You should have received copies of the GNU General Public License and the |
29 | | GNU Lesser General Public License along with the GNU MP Library. If not, |
30 | | see https://www.gnu.org/licenses/. */ |
31 | | |
32 | | #include <stdio.h> /* for NULL */ |
33 | | #include "gmp-impl.h" |
34 | | |
35 | | int |
36 | | mpz_root (mpz_ptr root, mpz_srcptr u, unsigned long int nth) |
37 | 56 | { |
38 | 56 | mp_ptr rootp, up; |
39 | 56 | mp_size_t us, un, rootn, remn; |
40 | 56 | TMP_DECL; |
41 | | |
42 | 56 | us = SIZ(u); |
43 | | |
44 | | /* even roots of negatives provoke an exception */ |
45 | 56 | if (UNLIKELY (us < 0 && (nth & 1) == 0)) |
46 | 0 | SQRT_OF_NEGATIVE; |
47 | | |
48 | 56 | if (UNLIKELY (nth <= 1)) |
49 | 0 | { |
50 | | /* root extraction interpreted as c^(1/nth) means a zeroth root should |
51 | | provoke a divide by zero, do this even if c==0 */ |
52 | 0 | if (UNLIKELY (nth == 0)) |
53 | 0 | DIVIDE_BY_ZERO; |
54 | | /* nth == 1 */ |
55 | 0 | if (root != NULL && u != root) |
56 | 0 | mpz_set (root, u); |
57 | 0 | return 1; /* exact result */ |
58 | 0 | } |
59 | | |
60 | 56 | if (us == 0) |
61 | 1 | { |
62 | 1 | if (root != NULL) |
63 | 1 | SIZ(root) = 0; |
64 | 1 | return 1; /* exact result */ |
65 | 1 | } |
66 | | |
67 | 55 | un = ABS (us); |
68 | 55 | rootn = (un - 1) / nth + 1; |
69 | | |
70 | 55 | TMP_MARK; |
71 | | |
72 | | /* FIXME: Perhaps disallow root == NULL */ |
73 | 55 | if (root != NULL && u != root) |
74 | 28 | rootp = MPZ_NEWALLOC (root, rootn); |
75 | 27 | else |
76 | 27 | rootp = TMP_ALLOC_LIMBS (rootn); |
77 | | |
78 | 55 | up = PTR(u); |
79 | 55 | remn = mpn_rootrem (rootp, NULL, up, un, (mp_limb_t) nth); |
80 | | |
81 | 55 | if (root != NULL) |
82 | 55 | { |
83 | 55 | SIZ(root) = us >= 0 ? rootn : -rootn; |
84 | 55 | if (u == root) |
85 | 27 | MPN_COPY (up, rootp, rootn); |
86 | 55 | } |
87 | | |
88 | 55 | TMP_FREE; |
89 | 55 | return remn == 0; |
90 | 55 | } |