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/**************************************************************************
* *
* Regina - A Normal Surface Theory Calculator *
* Computational Engine *
* *
* Copyright (c) 1999-2011, Ben Burton *
* For further details contact Ben Burton (bab@debian.org). *
* *
* This program is free software; you can redistribute it and/or *
* modify it under the terms of the GNU General Public License as *
* published by the Free Software Foundation; either version 2 of the *
* License, or (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, but *
* WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* General Public License for more details. *
* *
* You should have received a copy of the GNU General Public *
* License along with this program; if not, write to the Free *
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, *
* MA 02110-1301, USA. *
* *
**************************************************************************/
/* end stub */
/*! \file maths/permconv.h
* \brief Conversions between various permutation classes.
*/
#ifndef __PERMCONV_H
#ifndef __DOXYGEN
#define __PERMCONV_H
#endif
#include "regina-core.h"
#include "maths/nperm3.h"
#include "maths/nperm4.h"
#include "maths/nperm5.h"
namespace regina {
/**
* \weakgroup maths
* @{
*/
/**
* Converts the given 4-element permutation to a 5-element permutation.
* The resulting 5-element permutation will map 4 to 4, and will map
* 0, 1, 2 and 3 to their respective images under \a p.
*
* @param p the given 4-element permutation.
* @return the permutation \a p expressed as a permutation of five
* elements, not four.
*/
REGINA_API NPerm5 perm4to5(const NPerm4& p);
/**
* Expresses the given 5-element permutation as a 4-element permutation.
* The resulting 4-element permutation will map 0, 1, 2 and 3 to their
* respective images under \a p. It is assumed that the image of 4 is 4
* under \a p; otherwise this conversion cannot be performed.
*
* \pre The given permutation maps 4 to 4.
*
* @param p the given 5-element permutation.
* @return the permutation \a p expressed as a permutation of four
* elements, not five.
*/
REGINA_API NPerm4 perm5to4(const NPerm5& p);
/**
* Converts the given 3-element permutation to a 4-element permutation.
* The resulting 4-element permutation will map 3 to 3, and will map
* 0, 1 and 2 to their respective images under \a p.
*
* @param p the given 3-element permutation.
* @return the permutation \a p expressed as a permutation of four
* elements, not three.
*/
REGINA_API NPerm4 perm3to4(const NPerm3& p);
/**
* Expresses the given 4-element permutation as a 3-element permutation.
* The resulting 3-element permutation will map 0, 1 and 2 to their
* respective images under \a p. It is assumed that the image of 3 is 3
* under \a p; otherwise this conversion cannot be performed.
*
* \pre The given permutation maps 3 to 3.
*
* @param p the given 4-element permutation.
* @return the permutation \a p expressed as a permutation of three
* elements, not four.
*/
REGINA_API NPerm3 perm4to3(const NPerm4& p);
/*@}*/
// Inline conversion functions
inline NPerm5 perm4to5(const NPerm4& p) {
return NPerm5(p[0], p[1], p[2], p[3], 4);
}
inline NPerm4 perm5to4(const NPerm5& p) {
unsigned code = p.getPermCode();
return NPerm4(code & 0x03, (code >> 3) & 0x03,
(code >> 6) & 0x03, (code >> 9) & 0x03);
}
inline NPerm4 perm3to4(const NPerm3& p) {
// Code map: 0,1,2,3,4,5 -> 0,3,8,7,12,15.
unsigned char c = p.getPermCode();
return NPerm4::fromPermCode2(c == 2 ? 8 : c == 3 ? 7 : 3 * c);
}
inline NPerm3 perm4to3(const NPerm4& p) {
// Code map: 0,3,8,7,12,15 -> 0,1,2,3,4,5.
unsigned char c = p.getPermCode2();
return NPerm3::fromPermCode(c == 8 ? 2 : c == 7 ? 3 : c / 3);
}
} // namespace regina
#endif
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