1 #ifndef LIB2GEOM_UTILS_HEADER
2 #define LIB2GEOM_UTILS_HEADER
4 /**
5 * \file
6 * \brief Various utility functions.
7 *
8 * Copyright 2007 Johan Engelen <goejendaagh@zonnet.nl>
9 * Copyright 2006 Michael G. Sloan <mgsloan@gmail.com>
10 *
11 * This library is free software; you can redistribute it and/or
12 * modify it either under the terms of the GNU Lesser General Public
13 * License version 2.1 as published by the Free Software Foundation
14 * (the "LGPL") or, at your option, under the terms of the Mozilla
15 * Public License Version 1.1 (the "MPL"). If you do not alter this
16 * notice, a recipient may use your version of this file under either
17 * the MPL or the LGPL.
18 *
19 * You should have received a copy of the LGPL along with this library
20 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 * You should have received a copy of the MPL along with this library
23 * in the file COPYING-MPL-1.1
24 *
25 * The contents of this file are subject to the Mozilla Public License
26 * Version 1.1 (the "License"); you may not use this file except in
27 * compliance with the License. You may obtain a copy of the License at
28 * http://www.mozilla.org/MPL/
29 *
30 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
31 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
32 * the specific language governing rights and limitations.
33 *
34 */
36 #include <cmath>
37 #include <vector>
39 namespace Geom {
41 // proper logical xor
42 inline bool logical_xor (bool a, bool b) { return (a || b) && !(a && b); }
44 /** Sign function - indicates the sign of a numeric type. -1 indicates negative, 1 indicates
45 * positive, and 0 indicates, well, 0. Mathsy people will know this is basically the derivative
46 * of abs, except for the fact that it is defined on 0.
47 */
48 template <class T> inline int sgn(const T& x) {return (x < 0 ? -1 : (x > 0 ? 1 : 0) );}
50 template <class T> inline T sqr(const T& x) {return x * x;}
51 template <class T> inline T cube(const T& x) {return x * x * x;}
53 /** Between function - returns true if a number x is within a range. The values delimiting the
54 * range and the number must have the same type.
55 */
56 template <class T> inline const T& between (const T& min, const T& max, const T& x)
57 { return min < x && max > x; }
59 /** Returns x rounded to the nearest integer. It is unspecified what happens
60 * if x is half way between two integers: we may in future use rint/round
61 * on platforms that have them.
62 */
63 inline double round(double const x) { return std::floor(x + .5); }
65 /** Returns x rounded to the nearest \a places decimal places.
67 Implemented in terms of round, i.e. we make no guarantees as to what happens if x is
68 half way between two rounded numbers.
70 Note: places is the number of decimal places without using scientific (e) notation, not the
71 number of significant figures. This function may not be suitable for values of x whose
72 magnitude is so far from 1 that one would want to use scientific (e) notation.
74 places may be negative: e.g. places = -2 means rounding to a multiple of .01
75 **/
76 inline double decimal_round(double const x, int const places) {
77 //TODO: possibly implement with modulus instead?
78 double const multiplier = std::pow(10.0, places);
79 return round( x * multiplier ) / multiplier;
80 }
83 void binomial_coefficients(std::vector<size_t>& bc, size_t n);
85 }
87 #endif
89 /*
90 Local Variables:
91 mode:c++
92 c-file-style:"stroustrup"
93 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
94 indent-tabs-mode:nil
95 fill-column:99
96 End:
97 */
98 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :