source: libcaca/branches/0.7/src/math.c @ 4104

Last change on this file since 4104 was 298, checked in by Sam Hocevar, 16 years ago
  • doc/doxygen.cfg.in: + Removed caca_internal.h from the list of documented files.
  • src/: + Minor documentation updates.
  • Property svn:keywords set to Id
File size: 2.2 KB
Line 
1/*
2 *  libcaca       ASCII-Art library
3 *  Copyright (c) 2002, 2003 Sam Hocevar <sam@zoy.org>
4 *                All Rights Reserved
5 *
6 *  This library is free software; you can redistribute it and/or
7 *  modify it under the terms of the GNU Lesser General Public
8 *  License as published by the Free Software Foundation; either
9 *  version 2 of the License, or (at your option) any later version.
10 *
11 *  This library is distributed in the hope that it will be useful,
12 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 *  Lesser General Public License for more details.
15 *
16 *  You should have received a copy of the GNU Lesser General Public
17 *  License along with this library; if not, write to the Free Software
18 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19 *  02111-1307  USA
20 */
21
22/** \file math.c
23 *  \version \$Id: math.c 298 2003-12-31 14:21:08Z sam $
24 *  \author Sam Hocevar <sam@zoy.org>
25 *  \brief Math
26 *
27 *  This file contains simple mathematical routines.
28 */
29
30#include "config.h"
31
32#include <stdlib.h>
33
34#include "caca.h"
35#include "caca_internals.h"
36
37/**
38 * \brief Generate a random integer within a range.
39 *
40 * \param min The lower bound of the integer range.
41 * \param max The upper bound of the integer range.
42 * \return A random integer comprised between \p min and \p max, inclusive.
43 */
44int caca_rand(int min, int max)
45{
46    return min + (int)((1.0*(max-min+1)) * rand() / (RAND_MAX+1.0));
47}
48
49/**
50 * \brief Approximate a square root, using Newton's method to avoid
51 *        costly floating point calculations.
52 *
53 * \param a A positive integer.
54 * \return The approximate square root of \p a.
55 */
56unsigned int caca_sqrt(unsigned int a)
57{
58    if(a == 0)
59        return 0;
60
61    if(a < 1000000000)
62    {
63        unsigned int x = a < 10 ? 1
64                       : a < 1000 ? 10
65                       : a < 100000 ? 100
66                       : a < 10000000 ? 1000
67                       : 10000;
68
69        /* Newton's method. Three iterations would be more than enough. */
70        x = (x * x + a) / x / 2;
71        x = (x * x + a) / x / 2;
72        x = (x * x + a) / x / 2;
73        x = (x * x + a) / x / 2;
74
75        return x;
76    }
77
78    return 2 * caca_sqrt(a / 4);
79}
80
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