1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
|
/* Auxiliary functions for GMP-ECM.
Copyright 2002, 2003, 2004, 2005, 2007 Paul Zimmermann, Alexander Kruppa, Laurent Fousse, Jim Fougeron.
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 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 General Public License for
more details.
You should have received a copy of the GNU General Public License along
with this program; see the file COPYING. If not, write to the Free
Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
02111-1307, USA.
*/
#include <gmp.h>
#include "ecm-ecm.h"
/******************************************************************************
* *
* Auxiliary functions *
* *
******************************************************************************/
/* returns the number of decimal digits of n */
unsigned int
nb_digits (const mpz_t n)
{
mpz_t x;
unsigned int size;
size = mpz_sizeinbase (n, 10);
/* the GMP documentation says mpz_sizeinbase returns the exact value,
or one too big, thus:
(a) either n < 10^(size-1), and n has size-1 digits
(b) or n >= size-1, and n has size digits
Note: mpz_sizeinbase returns 1 for n=0, thus we always have size >= 1.
*/
mpz_init (x);
mpz_ui_pow_ui (x, 10, size - 1);
if (mpz_cmp (n, x) < 0)
size --;
mpz_clear (x);
return size;
}
|
