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104 lines
2.9 KiB
104 lines
2.9 KiB
5 days ago
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// This file is part of Bertini 2.
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//
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// double_extensions.hpp is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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//(at your option) any later version.
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//
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// double_extensions.hpp is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with double_extensions.hpp. If not, see
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// <http://www.gnu.org/licenses/>.
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//
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// Copyright(C) 2015 - 2017 by Bertini2 Development Team
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//
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// See <http://www.gnu.org/licenses/> for a copy of the license,
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// as well as COPYING. Bertini2 is provided with permitted
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// additional terms in the b2/licenses/ directory.
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// individual authors of this file include:
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// silviana amethyst, University of Wisconsin Eau Claire
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/**
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\file double_extensions.hpp
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\brief Provides bertini extensions to the double and complex<double> types.
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*/
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#pragma once
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#include <complex>
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#include <random>
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namespace bertini {
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using dbl = std::complex<double>;
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using dbl_complex = std::complex<double>;
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/**
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\brief Overload * for unsigned * complex<double>
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*/
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inline std::complex<double> operator*(unsigned i, std::complex<double> z) {
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z *= i;
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return z;
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}
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/**
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an overload of isnan, for std::complex<double>
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*/
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inline bool isnan(std::complex<double> const& z) {
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using std::isnan;
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return isnan(z.real()) || isnan(z.imag());
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}
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/**
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\brief Gets you a random real number between -1 and 1, fwiw
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*/
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inline double rand_real() {
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static std::default_random_engine generator;
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static std::uniform_real_distribution<double> distribution(-1.0, 1.0);
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return distribution(generator);
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}
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/**
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Compute +,- integral powers of a std::complex<double> number.
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This function recursively calls itself if the power is negative, by computing
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the power on the inverse.
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\note This overload was removed from C++ in C++11, for some insane reason. Here
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it is, back in black.
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*/
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inline dbl pow(const dbl& z, int power) {
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if (power < 0) {
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return pow(1. / z, -power);
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} else if (power == 0)
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return dbl(1, 0);
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else if (power == 1)
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return z;
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else if (power == 2)
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return z * z;
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else if (power == 3)
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return z * z * z;
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else {
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unsigned int p(power);
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dbl result(1, 0), z_to_the_current_power_of_two = z;
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// have copy of p in memory, can freely modify it.
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do {
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if ((p & 1) == 1) { // get the lowest bit of the number
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result *= z_to_the_current_power_of_two;
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}
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z_to_the_current_power_of_two *=
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z_to_the_current_power_of_two; // square
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// z_to_the_current_power_of_two
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} while (p >>= 1);
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return result;
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}
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}
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} // namespace bertini
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