128 lines
2.9 KiB
C++
128 lines
2.9 KiB
C++
/*
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LA: linear algebra C++ interface library
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Copyright (C) 2021 Jiri Pittner <jiri.pittner@jh-inst.cas.cz> or <jiri@pittnerovi.com>
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This program 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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This program 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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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "permutation.h"
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namespace LA {
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template <typename T>
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void NRPerm<T>::identity()
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{
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T n=this->size();
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#ifdef DEBUG
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if(n<0) laerror("invalid permutation size");
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#endif
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if(n==0) return;
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for(T i=1; i<=n; ++i) (*this)[i]=i;
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}
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template <typename T>
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bool NRPerm<T>::is_identity() const
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{
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T n=this->size();
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#ifdef DEBUG
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if(n<0) laerror("invalid permutation size");
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#endif
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if(n==0) return 1;
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for(T i=1; i<=n; ++i) if((*this)[i]!=i) return 0;
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return 1;
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}
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template <typename T>
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bool NRPerm<T>::is_valid() const
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{
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T n = this->size();
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if(n<0) return 0;
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NRVec_from1<T> used(n);
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used.clear();
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for(T i=1; i<=n; ++i)
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{
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T x= (*this)[i];
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if(x<1||x>n) return 0;
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used[x] += 1;
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}
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for(T i=1; i<=n; ++i) if(used[i]!=1) return 0;
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return 1;
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}
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template <typename T>
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NRPerm<T> NRPerm<T>::inverse() const
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{
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#ifdef DEBUG
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if(!this->is_valid()) laerror("inverse of invalid permutation");
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#endif
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NRPerm<T> q(this->size());
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for(T i=1; i<=this->size(); ++i) q[(*this)[i]]=i;
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return q;
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}
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template <typename T>
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NRPerm<T> NRPerm<T>::operator*(const NRPerm<T> q) const
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{
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#ifdef DEBUG
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if(!this->is_valid() || !q.is_valid()) laerror("multiplication of invalid permutation");
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#endif
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T n=this->size();
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if(n!=q.size()) laerror("product of incompatible permutations");
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NRPerm<T> r(n);
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for(T i=1; i<=n; ++i) r[i] = (*this)[q[i]];
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return r;
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}
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template <typename T>
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NRPerm<T> NRPerm<T>::conjugate_by(const NRPerm<T> q) const
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{
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#ifdef DEBUG
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if(!this->is_valid() || !q.is_valid()) laerror("multiplication of invalid permutation");
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#endif
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T n=this->size();
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if(n!=q.size()) laerror("product of incompatible permutations");
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NRPerm<T> qi=q.inverse();
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NRPerm<T> r(n);
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for(T i=1; i<=n; ++i) r[i] = qi[(*this)[q[i]]];
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return r;
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}
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template <typename T>
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int NRPerm<T>::parity() const
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{
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if(!this->is_valid()) return 0;
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T n=this->size();
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if(n==1) return 1;
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T count=0;
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for(T i=2;i<=n;i++) for(T j=1;j<i;j++) if((*this)[j]>(*this)[i]) count++;
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return (count&1)? -1:1;
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}
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/***************************************************************************//**
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* forced instantization in the corresponding object file
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******************************************************************************/
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template class NRPerm<int>;
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}
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