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progressing implementation of permutations

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This commit is contained in:
Jiri Pittner
2021-05-13 16:45:10 +02:00
parent 01665674c5
commit 60e8a379f5
9 changed files with 201 additions and 6 deletions
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61
permutation.cc
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@@ -19,6 +19,32 @@
#include "permutation.h"
namespace LA {
template <typename T>
void NRPerm<T>::identity()
{
T n=this->size();
#ifdef DEBUG
if(n<0) laerror("invalid permutation size");
#endif
if(n==0) return;
for(T i=1; i<=n; ++i) (*this)[i]=i;
}
template <typename T>
bool NRPerm<T>::is_identity() const
{
T n=this->size();
#ifdef DEBUG
if(n<0) laerror("invalid permutation size");
#endif
if(n==0) return 1;
for(T i=1; i<=n; ++i) if((*this)[i]!=i) return 0;
return 1;
}
template <typename T>
bool NRPerm<T>::is_valid() const
{
@@ -39,6 +65,10 @@ return 1;
template <typename T>
NRPerm<T> NRPerm<T>::inverse() const
{
#ifdef DEBUG
if(!this->is_valid()) laerror("inverse of invalid permutation");
#endif
NRPerm<T> q(this->size());
for(T i=1; i<=this->size(); ++i) q[(*this)[i]]=i;
return q;
@@ -48,15 +78,44 @@ return q;
template <typename T>
NRPerm<T> NRPerm<T>::operator*(const NRPerm<T> q) const
{
#ifdef DEBUG
if(!this->is_valid() || !q.is_valid()) laerror("multiplication of invalid permutation");
#endif
T n=this->size();
if(n!=q.size()) laerror("product of incompatible permutations");
NRPerm<T> r(n);
for(T i=1; i<=n; ++i) r[i] = q[(*this)[i]];
for(T i=1; i<=n; ++i) r[i] = (*this)[q[i]];
return r;
}
template <typename T>
NRPerm<T> NRPerm<T>::conjugate_by(const NRPerm<T> q) const
{
#ifdef DEBUG
if(!this->is_valid() || !q.is_valid()) laerror("multiplication of invalid permutation");
#endif
T n=this->size();
if(n!=q.size()) laerror("product of incompatible permutations");
NRPerm<T> qi=q.inverse();
NRPerm<T> r(n);
for(T i=1; i<=n; ++i) r[i] = qi[(*this)[q[i]]];
return r;
}
template <typename T>
int NRPerm<T>::parity() const
{
if(!this->is_valid()) return 0;
T n=this->size();
if(n==1) return 1;
T count=0;
for(T i=2;i<=n;i++) for(T j=1;j<i;j++) if((*this)[j]>(*this)[i]) count++;
return (count&1)? -1:1;
}