math-utils.h

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/*
 * Authors:
 *   Johan Engelen <goejendaagh@zonnet.nl>
 *   Michael G. Sloan <mgsloan@gmail.com>
 *   Krzysztof Kosiński <tweenk.pl@gmail.com>
 * Copyright 2006-2009 Authors
 *
 * 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.
 *
 */
 
#ifndef LIB2GEOM_SEEN_MATH_UTILS_H
#define LIB2GEOM_SEEN_MATH_UTILS_H
 
#include <math.h> // sincos is usually only available in math.h
#include <array>
#include <cmath>
#include <utility> // for std::pair
#include <boost/math/special_functions/fpclassify.hpp>
 
namespace Geom {
 
template <class T> inline int sgn(const T& x) {
    return (x < 0 ? -1 : (x > 0 ? 1 : 0) );
// can we 'optimize' this with:
//    return ( (T(0) < x) - (x < T(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;}
 
template <class T> inline const T& between (const T& min, const T& max, const T& x)
    { return (min < x) && (max > x); }
 
inline double decimal_round(double x, int p) {
    //TODO: possibly implement with modulus instead?
    double const multiplier = ::pow(10.0, p);
    return ::round( x * multiplier ) / multiplier;
}
 
inline void sincos(double angle, double &sin_, double &cos_) {
#ifdef HAVE_SINCOS
    ::sincos(angle, &sin_, &cos_);
#else
    sin_ = ::sin(angle);
    cos_ = ::cos(angle);
#endif
}
 
template <size_t N>
inline int rescale_homogenous(std::array<double, N> &values)
{
    if constexpr (N == 0) {
        return 0;
    }
    std::array<int, N> exponents;
    std::array<double, N> mantissas;
    int average = 0;
    for (size_t i = 0; i < N; i++) {
        mantissas[i] = std::frexp(values[i], &exponents[i]);
        average += exponents[i];
    }
    average /= (int)N;
    for (size_t i = 0; i < N; i++) {
        values[i] = std::ldexp(mantissas[i], exponents[i] - average);
    }
    return -average;
}
 
} // end namespace Geom
 
#endif // LIB2GEOM_SEEN_MATH_UTILS_H
 
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*/
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