utils.h revision 8001ba81cb851b38d86650a2fef5817facffb763
#ifndef LIB2GEOM_UTILS_HEADER
#define LIB2GEOM_UTILS_HEADER
/** Various utility functions.
*
* Copyright 2007 Johan Engelen <goejendaagh@zonnet.nl>
* Copyright 2006 Michael G. Sloan <mgsloan@gmail.com>
*
* This library is free software; you can redistribute it and/or
* modify it either under the terms of the GNU Lesser General Public
* License version 2.1 as published by the Free Software Foundation
* (the "LGPL") or, at your option, under the terms of the Mozilla
* Public License Version 1.1 (the "MPL"). If you do not alter this
* notice, a recipient may use your version of this file under either
* the MPL or the LGPL.
*
* You should have received a copy of the LGPL along with this library
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
* You should have received a copy of the MPL along with this library
* in the file COPYING-MPL-1.1
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
* the specific language governing rights and limitations.
*
*/
#include <cmath>
#include <vector>
namespace Geom {
// proper logical xor
inline bool logical_xor (bool a, bool b) { return (a || b) && !(a && b); }
/** Sign function - indicates the sign of a numeric type. -1 indicates negative, 1 indicates
* positive, and 0 indicates, well, 0. Mathsy people will know this is basically the derivative
* of abs, except for the fact that it is defined on 0.
*/
template <class T> inline int sgn(const T& x) {return (x < 0 ? -1 : (x > 0 ? 1 : 0) );}
template <class T> inline T sqr(const T& x) {return x * x;}
template <class T> inline T cube(const T& x) {return x * x * x;}
/** Between function - returns true if a number x is within a range. The values delimiting the
* range and the number must have the same type.
*/
template <class T> inline const T& between (const T& min, const T& max, const T& x)
{ return min < x && max > x; }
/** Returns x rounded to the nearest integer. It is unspecified what happens
* if x is half way between two integers: we may in future use rint/round
* on platforms that have them.
*/
inline double round(double const x) { return std::floor(x + .5); }
/** Returns x rounded to the nearest \a places decimal places.
Implemented in terms of round, i.e. we make no guarantees as to what happens if x is
half way between two rounded numbers.
Note: places is the number of decimal places without using scientific (e) notation, not the
number of significant figures. This function may not be suitable for values of x whose
magnitude is so far from 1 that one would want to use scientific (e) notation.
places may be negative: e.g. places = -2 means rounding to a multiple of .01
**/
inline double decimal_round(double const x, int const places) {
//TODO: possibly implement with modulus instead?
double const multiplier = std::pow(10.0, places);
return round( x * multiplier ) / multiplier;
}
void binomial_coefficients(std::vector<size_t>& bc, size_t n);
}
#endif
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
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