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/* |
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* Copyright (c) 2005 The University of Notre Dame. All Rights Reserved. |
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* |
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* The University of Notre Dame grants you ("Licensee") a |
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* non-exclusive, royalty free, license to use, modify and |
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* redistribute this software in source and binary code form, provided |
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* that the following conditions are met: |
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* |
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* 1. Acknowledgement of the program authors must be made in any |
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* publication of scientific results based in part on use of the |
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* program. An acceptable form of acknowledgement is citation of |
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* the article in which the program was described (Matthew |
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* A. Meineke, Charles F. Vardeman II, Teng Lin, Christopher |
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* J. Fennell and J. Daniel Gezelter, "OOPSE: An Object-Oriented |
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* Parallel Simulation Engine for Molecular Dynamics," |
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* J. Comput. Chem. 26, pp. 252-271 (2005)) |
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* |
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* 2. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* 3. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the |
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* distribution. |
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* |
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* This software is provided "AS IS," without a warranty of any |
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* kind. All express or implied conditions, representations and |
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* warranties, including any implied warranty of merchantability, |
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* fitness for a particular purpose or non-infringement, are hereby |
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* excluded. The University of Notre Dame and its licensors shall not |
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* be liable for any damages suffered by licensee as a result of |
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* using, modifying or distributing the software or its |
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* derivatives. In no event will the University of Notre Dame or its |
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* licensors be liable for any lost revenue, profit or data, or for |
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* direct, indirect, special, consequential, incidental or punitive |
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* damages, however caused and regardless of the theory of liability, |
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* arising out of the use of or inability to use software, even if the |
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* University of Notre Dame has been advised of the possibility of |
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* such damages. |
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*/ |
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|
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/** |
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* @file Polynomial.hpp |
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* @author teng lin |
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* @date 11/16/2004 |
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* @version 1.0 |
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*/ |
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|
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#ifndef MATH_POLYNOMIAL_HPP |
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#define MATH_POLYNOMIAL_HPP |
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|
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#include <iostream> |
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#include <list> |
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#include <map> |
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#include <utility> |
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#include <complex> |
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#include "config.h" |
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#include "math/Eigenvalue.hpp" |
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|
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namespace oopse { |
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|
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template<typename Real> Real fastpow(Real x, int N) { |
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Real result(1); //or 1.0? |
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|
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for (int i = 0; i < N; ++i) { |
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result *= x; |
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} |
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|
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return result; |
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} |
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|
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/** |
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* @class Polynomial Polynomial.hpp "math/Polynomial.hpp" |
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* A generic Polynomial class |
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*/ |
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template<typename Real> |
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class Polynomial { |
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|
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public: |
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typedef Polynomial<Real> PolynomialType; |
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typedef int ExponentType; |
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typedef Real CoefficientType; |
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typedef std::map<ExponentType, CoefficientType> PolynomialPairMap; |
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typedef typename PolynomialPairMap::iterator iterator; |
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typedef typename PolynomialPairMap::const_iterator const_iterator; |
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|
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Polynomial() {} |
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Polynomial(Real v) {setCoefficient(0, v);} |
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/** |
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* Calculates the value of this Polynomial evaluated at the given x value. |
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* @return The value of this Polynomial evaluates at the given x value |
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* @param x the value of the independent variable for this |
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* Polynomial function |
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*/ |
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Real evaluate(const Real& x) { |
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Real result = Real(); |
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ExponentType exponent; |
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CoefficientType coefficient; |
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|
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for (iterator i = polyPairMap_.begin(); i != polyPairMap_.end(); ++i) { |
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exponent = i->first; |
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coefficient = i->second; |
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result += fastpow(x, exponent) * coefficient; |
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} |
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|
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return result; |
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} |
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|
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/** |
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* Returns the first derivative of this polynomial. |
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* @return the first derivative of this polynomial |
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* @param x |
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*/ |
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Real evaluateDerivative(const Real& x) { |
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Real result = Real(); |
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ExponentType exponent; |
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CoefficientType coefficient; |
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|
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for (iterator i = polyPairMap_.begin(); i != polyPairMap_.end(); ++i) { |
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exponent = i->first; |
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coefficient = i->second; |
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result += fastpow(x, exponent - 1) * coefficient * exponent; |
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} |
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|
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return result; |
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} |
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|
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|
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/** |
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* Set the coefficent of the specified exponent, if the |
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* coefficient is already there, it will be overwritten. |
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* @param exponent exponent of a term in this Polynomial |
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* @param coefficient multiplier of a term in this Polynomial |
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*/ |
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void setCoefficient(int exponent, const Real& coefficient) { |
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polyPairMap_[exponent] = coefficient; |
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} |
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|
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/** |
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* Set the coefficent of the specified exponent. If the |
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* coefficient is already there, just add the new coefficient to |
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* the old one, otherwise, just call setCoefficent |
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* @param exponent exponent of a term in this Polynomial |
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* @param coefficient multiplier of a term in this Polynomial |
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*/ |
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void addCoefficient(int exponent, const Real& coefficient) { |
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iterator i = polyPairMap_.find(exponent); |
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|
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if (i != end()) { |
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i->second += coefficient; |
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} else { |
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setCoefficient(exponent, coefficient); |
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} |
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} |
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|
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/** |
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* Returns the coefficient associated with the given power for |
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* this Polynomial. |
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* @return the coefficient associated with the given power for |
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* this Polynomial |
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* @exponent exponent of any term in this Polynomial |
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*/ |
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Real getCoefficient(ExponentType exponent) { |
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iterator i = polyPairMap_.find(exponent); |
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|
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if (i != end()) { |
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return i->second; |
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} else { |
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return Real(0); |
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} |
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} |
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|
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iterator begin() { |
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return polyPairMap_.begin(); |
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} |
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|
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const_iterator begin() const{ |
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return polyPairMap_.begin(); |
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} |
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|
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iterator end() { |
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return polyPairMap_.end(); |
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} |
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|
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const_iterator end() const{ |
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return polyPairMap_.end(); |
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} |
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|
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iterator find(ExponentType exponent) { |
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return polyPairMap_.find(exponent); |
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} |
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|
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size_t size() { |
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return polyPairMap_.size(); |
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} |
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|
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int degree() { |
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int deg = 0; |
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for (iterator i = polyPairMap_.begin(); i != polyPairMap_.end(); ++i) { |
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if (i->first > deg) |
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deg = i->first; |
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} |
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return deg; |
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} |
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|
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PolynomialType& operator = (const PolynomialType& p) { |
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|
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if (this != &p) // protect against invalid self-assignment |
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{ |
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typename Polynomial<Real>::const_iterator i; |
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|
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polyPairMap_.clear(); // clear out the old map |
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|
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for (i = p.begin(); i != p.end(); ++i) { |
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this->setCoefficient(i->first, i->second); |
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} |
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} |
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// by convention, always return *this |
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return *this; |
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} |
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|
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PolynomialType& operator += (const PolynomialType& p) { |
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typename Polynomial<Real>::const_iterator i; |
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|
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for (i = p.begin(); i != p.end(); ++i) { |
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this->addCoefficient(i->first, i->second); |
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} |
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|
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return *this; |
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} |
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|
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PolynomialType& operator -= (const PolynomialType& p) { |
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typename Polynomial<Real>::const_iterator i; |
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for (i = p.begin(); i != p.end(); ++i) { |
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this->addCoefficient(i->first, -i->second); |
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} |
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return *this; |
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} |
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|
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PolynomialType& operator *= (const PolynomialType& p) { |
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typename Polynomial<Real>::const_iterator i; |
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typename Polynomial<Real>::const_iterator j; |
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Polynomial<Real> p2(*this); |
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|
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polyPairMap_.clear(); // clear out old map |
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for (i = p2.begin(); i !=p2.end(); ++i) { |
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for (j = p.begin(); j !=p.end(); ++j) { |
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this->addCoefficient( i->first + j->first, i->second * j->second); |
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} |
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} |
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return *this; |
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} |
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|
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//PolynomialType& operator *= (const Real v) |
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PolynomialType& operator *= (const Real v) { |
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typename Polynomial<Real>::const_iterator i; |
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//Polynomial<Real> result; |
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|
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for (i = this->begin(); i != this->end(); ++i) { |
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this->setCoefficient( i->first, i->second*v); |
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} |
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|
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return *this; |
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} |
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|
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PolynomialType& operator += (const Real v) { |
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this->addCoefficient( 0, v); |
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return *this; |
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} |
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|
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/** |
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* Returns the first derivative of this polynomial. |
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* @return the first derivative of this polynomial |
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*/ |
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PolynomialType & getDerivative() { |
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Polynomial<Real> p(); |
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|
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typename Polynomial<Real>::const_iterator i; |
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ExponentType exponent; |
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CoefficientType coefficient; |
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|
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for (i = this->begin(); i != this->end(); ++i) { |
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exponent = i->first; |
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coefficient = i->second; |
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p.setCoefficient(exponent-1, coefficient * exponent); |
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} |
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|
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return p; |
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} |
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|
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// Creates the Companion matrix for a given polynomial |
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DynamicRectMatrix<Real> CreateCompanion() { |
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int rank = degree(); |
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DynamicRectMatrix<Real> mat(rank, rank); |
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Real majorCoeff = getCoefficient(rank); |
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for(int i = 0; i < rank; ++i) { |
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for(int j = 0; j < rank; ++j) { |
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if(i - j == 1) { |
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mat(i, j) = 1; |
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} else if(j == rank-1) { |
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mat(i, j) = -1 * getCoefficient(i) / majorCoeff; |
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} |
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} |
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} |
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return mat; |
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} |
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|
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// Find the Roots of a given polynomial |
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std::vector<complex<Real> > FindRoots() { |
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int rank = degree(); |
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DynamicRectMatrix<Real> companion = CreateCompanion(); |
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JAMA::Eigenvalue<Real> eig(companion); |
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DynamicVector<Real> reals, imags; |
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eig.getRealEigenvalues(reals); |
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eig.getImagEigenvalues(imags); |
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|
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std::vector<complex<Real> > roots; |
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for (int i = 0; i < rank; i++) { |
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roots.push_back(complex(reals(i), imags(i))); |
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} |
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|
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return roots; |
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} |
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|
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std::vector<Real> FindRealRoots() { |
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|
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const Real fEpsilon = 1.0e-8; |
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std::vector<Real> roots; |
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roots.clear(); |
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|
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const int deg = degree(); |
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|
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switch (deg) { |
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case 1: { |
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Real fC1 = getCoefficient(1); |
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Real fC0 = getCoefficient(0); |
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roots.push_back( -fC0 / fC1); |
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return roots; |
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} |
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break; |
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case 2: { |
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Real fC2 = getCoefficient(2); |
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Real fC1 = getCoefficient(1); |
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Real fC0 = getCoefficient(0); |
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Real fDiscr = fC1*fC1 - 4.0*fC0*fC2; |
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if (abs(fDiscr) <= fEpsilon) { |
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fDiscr = (Real)0.0; |
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} |
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|
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if (fDiscr < (Real)0.0) { // complex roots only |
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return roots; |
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} |
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|
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Real fTmp = ((Real)0.5)/fC2; |
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|
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if (fDiscr > (Real)0.0) { // 2 real roots |
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fDiscr = sqrt(fDiscr); |
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roots.push_back(fTmp*(-fC1 - fDiscr)); |
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roots.push_back(fTmp*(-fC1 + fDiscr)); |
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} else { |
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roots.push_back(-fTmp * fC1); // 1 real root |
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} |
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} |
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return roots; |
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break; |
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|
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case 3: { |
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Real fC3 = getCoefficient(3); |
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Real fC2 = getCoefficient(2); |
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Real fC1 = getCoefficient(1); |
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Real fC0 = getCoefficient(0); |
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|
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// make polynomial monic, x^3+c2*x^2+c1*x+c0 |
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Real fInvC3 = ((Real)1.0)/fC3; |
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fC0 *= fInvC3; |
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fC1 *= fInvC3; |
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fC2 *= fInvC3; |
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|
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// convert to y^3+a*y+b = 0 by x = y-c2/3 |
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const Real fThird = (Real)1.0/(Real)3.0; |
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const Real fTwentySeventh = (Real)1.0/(Real)27.0; |
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Real fOffset = fThird*fC2; |
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Real fA = fC1 - fC2*fOffset; |
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Real fB = fC0+fC2*(((Real)2.0)*fC2*fC2-((Real)9.0)*fC1)*fTwentySeventh; |
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Real fHalfB = ((Real)0.5)*fB; |
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|
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Real fDiscr = fHalfB*fHalfB + fA*fA*fA*fTwentySeventh; |
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if (fabs(fDiscr) <= fEpsilon) { |
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fDiscr = (Real)0.0; |
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} |
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|
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if (fDiscr > (Real)0.0) { // 1 real, 2 complex roots |
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|
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fDiscr = sqrt(fDiscr); |
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Real fTemp = -fHalfB + fDiscr; |
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Real root; |
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if (fTemp >= (Real)0.0) { |
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root = pow(fTemp,fThird); |
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} else { |
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root = -pow(-fTemp,fThird); |
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} |
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fTemp = -fHalfB - fDiscr; |
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if ( fTemp >= (Real)0.0 ) { |
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root += pow(fTemp,fThird); |
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} else { |
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root -= pow(-fTemp,fThird); |
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} |
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root -= fOffset; |
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|
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roots.push_back(root); |
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} else if (fDiscr < (Real)0.0) { |
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const Real fSqrt3 = sqrt((Real)3.0); |
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Real fDist = sqrt(-fThird*fA); |
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Real fAngle = fThird*atan2(sqrt(-fDiscr), -fHalfB); |
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Real fCos = cos(fAngle); |
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Real fSin = sin(fAngle); |
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roots.push_back(((Real)2.0)*fDist*fCos-fOffset); |
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roots.push_back(-fDist*(fCos+fSqrt3*fSin)-fOffset); |
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roots.push_back(-fDist*(fCos-fSqrt3*fSin)-fOffset); |
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} else { |
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Real fTemp; |
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if (fHalfB >= (Real)0.0) { |
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fTemp = -pow(fHalfB,fThird); |
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} else { |
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fTemp = pow(-fHalfB,fThird); |
426 |
} |
427 |
roots.push_back(((Real)2.0)*fTemp-fOffset); |
428 |
roots.push_back(-fTemp-fOffset); |
429 |
roots.push_back(-fTemp-fOffset); |
430 |
} |
431 |
} |
432 |
return roots; |
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break; |
434 |
case 4: { |
435 |
Real fC4 = getCoefficient(4); |
436 |
Real fC3 = getCoefficient(3); |
437 |
Real fC2 = getCoefficient(2); |
438 |
Real fC1 = getCoefficient(1); |
439 |
Real fC0 = getCoefficient(0); |
440 |
|
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// make polynomial monic, x^4+c3*x^3+c2*x^2+c1*x+c0 |
442 |
Real fInvC4 = ((Real)1.0)/fC4; |
443 |
fC0 *= fInvC4; |
444 |
fC1 *= fInvC4; |
445 |
fC2 *= fInvC4; |
446 |
fC3 *= fInvC4; |
447 |
|
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// reduction to resolvent cubic polynomial y^3+r2*y^2+r1*y+r0 = 0 |
449 |
Real fR0 = -fC3*fC3*fC0 + ((Real)4.0)*fC2*fC0 - fC1*fC1; |
450 |
Real fR1 = fC3*fC1 - ((Real)4.0)*fC0; |
451 |
Real fR2 = -fC2; |
452 |
Polynomial<Real> tempCubic; |
453 |
tempCubic.setCoefficient(0, fR0); |
454 |
tempCubic.setCoefficient(1, fR1); |
455 |
tempCubic.setCoefficient(2, fR2); |
456 |
tempCubic.setCoefficient(3, 1.0); |
457 |
std::vector<Real> cubeRoots = tempCubic.FindRealRoots(); // always |
458 |
// produces |
459 |
// at |
460 |
// least |
461 |
// one |
462 |
// root |
463 |
Real fY = cubeRoots[0]; |
464 |
|
465 |
Real fDiscr = ((Real)0.25)*fC3*fC3 - fC2 + fY; |
466 |
if (fabs(fDiscr) <= fEpsilon) { |
467 |
fDiscr = (Real)0.0; |
468 |
} |
469 |
|
470 |
if (fDiscr > (Real)0.0) { |
471 |
Real fR = sqrt(fDiscr); |
472 |
Real fT1 = ((Real)0.75)*fC3*fC3 - fR*fR - ((Real)2.0)*fC2; |
473 |
Real fT2 = (((Real)4.0)*fC3*fC2 - ((Real)8.0)*fC1 - fC3*fC3*fC3) / |
474 |
(((Real)4.0)*fR); |
475 |
|
476 |
Real fTplus = fT1+fT2; |
477 |
Real fTminus = fT1-fT2; |
478 |
if (fabs(fTplus) <= fEpsilon) { |
479 |
fTplus = (Real)0.0; |
480 |
} |
481 |
if (fabs(fTminus) <= fEpsilon) { |
482 |
fTminus = (Real)0.0; |
483 |
} |
484 |
|
485 |
if (fTplus >= (Real)0.0) { |
486 |
Real fD = sqrt(fTplus); |
487 |
roots.push_back(-((Real)0.25)*fC3+((Real)0.5)*(fR+fD)); |
488 |
roots.push_back(-((Real)0.25)*fC3+((Real)0.5)*(fR-fD)); |
489 |
} |
490 |
if (fTminus >= (Real)0.0) { |
491 |
Real fE = sqrt(fTminus); |
492 |
roots.push_back(-((Real)0.25)*fC3+((Real)0.5)*(fE-fR)); |
493 |
roots.push_back(-((Real)0.25)*fC3-((Real)0.5)*(fE+fR)); |
494 |
} |
495 |
} else if (fDiscr < (Real)0.0) { |
496 |
//roots.clear(); |
497 |
} else { |
498 |
Real fT2 = fY*fY-((Real)4.0)*fC0; |
499 |
if (fT2 >= -fEpsilon) { |
500 |
if (fT2 < (Real)0.0) { // round to zero |
501 |
fT2 = (Real)0.0; |
502 |
} |
503 |
fT2 = ((Real)2.0)*sqrt(fT2); |
504 |
Real fT1 = ((Real)0.75)*fC3*fC3 - ((Real)2.0)*fC2; |
505 |
if (fT1+fT2 >= fEpsilon) { |
506 |
Real fD = sqrt(fT1+fT2); |
507 |
roots.push_back( -((Real)0.25)*fC3+((Real)0.5)*fD); |
508 |
roots.push_back( -((Real)0.25)*fC3-((Real)0.5)*fD); |
509 |
} |
510 |
if (fT1-fT2 >= fEpsilon) { |
511 |
Real fE = sqrt(fT1-fT2); |
512 |
roots.push_back( -((Real)0.25)*fC3+((Real)0.5)*fE); |
513 |
roots.push_back( -((Real)0.25)*fC3-((Real)0.5)*fE); |
514 |
} |
515 |
} |
516 |
} |
517 |
} |
518 |
return roots; |
519 |
break; |
520 |
default: { |
521 |
DynamicRectMatrix<Real> companion = CreateCompanion(); |
522 |
JAMA::Eigenvalue<Real> eig(companion); |
523 |
DynamicVector<Real> reals, imags; |
524 |
eig.getRealEigenvalues(reals); |
525 |
eig.getImagEigenvalues(imags); |
526 |
|
527 |
for (int i = 0; i < deg; i++) { |
528 |
if (fabs(imags(i)) < fEpsilon) |
529 |
roots.push_back(reals(i)); |
530 |
} |
531 |
} |
532 |
return roots; |
533 |
break; |
534 |
} |
535 |
|
536 |
return roots; // should be empty if you got here |
537 |
} |
538 |
|
539 |
private: |
540 |
|
541 |
PolynomialPairMap polyPairMap_; |
542 |
}; |
543 |
|
544 |
|
545 |
/** |
546 |
* Generates and returns the product of two given Polynomials. |
547 |
* @return A Polynomial containing the product of the two given Polynomial parameters |
548 |
*/ |
549 |
template<typename Real> |
550 |
Polynomial<Real> operator *(const Polynomial<Real>& p1, const Polynomial<Real>& p2) { |
551 |
typename Polynomial<Real>::const_iterator i; |
552 |
typename Polynomial<Real>::const_iterator j; |
553 |
Polynomial<Real> p; |
554 |
|
555 |
for (i = p1.begin(); i !=p1.end(); ++i) { |
556 |
for (j = p2.begin(); j !=p2.end(); ++j) { |
557 |
p.addCoefficient( i->first + j->first, i->second * j->second); |
558 |
} |
559 |
} |
560 |
|
561 |
return p; |
562 |
} |
563 |
|
564 |
template<typename Real> |
565 |
Polynomial<Real> operator *(const Polynomial<Real>& p, const Real v) { |
566 |
typename Polynomial<Real>::const_iterator i; |
567 |
Polynomial<Real> result; |
568 |
|
569 |
for (i = p.begin(); i !=p.end(); ++i) { |
570 |
result.setCoefficient( i->first , i->second * v); |
571 |
} |
572 |
|
573 |
return result; |
574 |
} |
575 |
|
576 |
template<typename Real> |
577 |
Polynomial<Real> operator *( const Real v, const Polynomial<Real>& p) { |
578 |
typename Polynomial<Real>::const_iterator i; |
579 |
Polynomial<Real> result; |
580 |
|
581 |
for (i = p.begin(); i !=p.end(); ++i) { |
582 |
result.setCoefficient( i->first , i->second * v); |
583 |
} |
584 |
|
585 |
return result; |
586 |
} |
587 |
|
588 |
/** |
589 |
* Generates and returns the sum of two given Polynomials. |
590 |
* @param p1 the first polynomial |
591 |
* @param p2 the second polynomial |
592 |
*/ |
593 |
template<typename Real> |
594 |
Polynomial<Real> operator +(const Polynomial<Real>& p1, const Polynomial<Real>& p2) { |
595 |
Polynomial<Real> p(p1); |
596 |
|
597 |
typename Polynomial<Real>::const_iterator i; |
598 |
|
599 |
for (i = p2.begin(); i != p2.end(); ++i) { |
600 |
p.addCoefficient(i->first, i->second); |
601 |
} |
602 |
|
603 |
return p; |
604 |
|
605 |
} |
606 |
|
607 |
/** |
608 |
* Generates and returns the difference of two given Polynomials. |
609 |
* @return |
610 |
* @param p1 the first polynomial |
611 |
* @param p2 the second polynomial |
612 |
*/ |
613 |
template<typename Real> |
614 |
Polynomial<Real> operator -(const Polynomial<Real>& p1, const Polynomial<Real>& p2) { |
615 |
Polynomial<Real> p(p1); |
616 |
|
617 |
typename Polynomial<Real>::const_iterator i; |
618 |
|
619 |
for (i = p2.begin(); i != p2.end(); ++i) { |
620 |
p.addCoefficient(i->first, -i->second); |
621 |
} |
622 |
|
623 |
return p; |
624 |
|
625 |
} |
626 |
|
627 |
/** |
628 |
* Returns the first derivative of this polynomial. |
629 |
* @return the first derivative of this polynomial |
630 |
*/ |
631 |
template<typename Real> |
632 |
Polynomial<Real> getDerivative(const Polynomial<Real>& p1) { |
633 |
Polynomial<Real> p(); |
634 |
|
635 |
typename Polynomial<Real>::const_iterator i; |
636 |
ExponentType exponent; |
637 |
CoefficientType coefficient; |
638 |
|
639 |
for (i = p1.begin(); i != p1.end(); ++i) { |
640 |
exponent = i->first; |
641 |
coefficient = i->second; |
642 |
p.setCoefficient(exponent-1, coefficient * exponent); |
643 |
} |
644 |
|
645 |
return p; |
646 |
} |
647 |
|
648 |
/** |
649 |
* Tests if two polynomial have the same exponents |
650 |
* @return true if all of the exponents in these Polynomial are identical |
651 |
* @param p1 the first polynomial |
652 |
* @param p2 the second polynomial |
653 |
* @note this function does not compare the coefficient |
654 |
*/ |
655 |
template<typename Real> |
656 |
bool equal(const Polynomial<Real>& p1, const Polynomial<Real>& p2) { |
657 |
|
658 |
typename Polynomial<Real>::const_iterator i; |
659 |
typename Polynomial<Real>::const_iterator j; |
660 |
|
661 |
if (p1.size() != p2.size() ) { |
662 |
return false; |
663 |
} |
664 |
|
665 |
for (i = p1.begin(), j = p2.begin(); i != p1.end() && j != p2.end(); ++i, ++j) { |
666 |
if (i->first != j->first) { |
667 |
return false; |
668 |
} |
669 |
} |
670 |
|
671 |
return true; |
672 |
} |
673 |
|
674 |
|
675 |
|
676 |
typedef Polynomial<RealType> DoublePolynomial; |
677 |
|
678 |
} //end namespace oopse |
679 |
#endif //MATH_POLYNOMIAL_HPP |