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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 */
#ifndef __NMATRIXINT_H
#ifndef __DOXYGEN
#define __NMATRIXINT_H
#endif
/*! \file maths/nmatrixint.h
* \brief Deals with matrices of arbitrary precision integers.
*/
#include "regina-core.h"
#include "shareableobject.h"
#include "maths/nlargeinteger.h"
#include "maths/nmatrix.h"
namespace regina {
/**
* \weakgroup maths
* @{
*/
/**
* Represents a matrix of arbitrary precision integers.
* Calculations will be exact no matter how large the integers become.
*
* Note that many important functions (such as entry()) are inherited
* from the superclasses NMatrix and NMatrixRing, and are not documented
* again here.
*
* \ifacespython Most inherited member functions are implemented.
* Exceptions are noted in the documentation for each individual member
* function.
*/
class REGINA_API NMatrixInt :
public NMatrixRing<NLargeInteger>, public ShareableObject {
public:
/**
* Creates a new matrix of the given size.
* All entries will be initialised to zero.
*
* \pre The given number of rows and columns are
* both strictly positive.
*
* @param rows the number of rows in the new matrix.
* @param cols the number of columns in the new matrix.
*/
NMatrixInt(unsigned long rows, unsigned long cols);
/**
* Creates a new matrix that is a clone of the given matrix.
*
* @param cloneMe the matrix to clone.
*/
NMatrixInt(const NMatrixInt& cloneMe);
/**
* Divides all elements of the given row by the given integer.
* This can only be used when the given integer divides into all
* row elements exactly (with no remainder), and is much faster
* than ordinary division.
*
* \pre The argument \a divBy is neither zero nor infinity, and
* none of the elements of the given row are infinity.
* \pre The argument \a divBy divides exactly into every element
* of the given row (i.e., it leaves no remainder).
* \pre The given row number is between 0 and rows()-1 inclusive.
*
* @param row the index of the row whose elements should be
* divided by \a divBy.
* @param divBy the integer to divide each row element by.
*/
void divRowExact(unsigned long row, const NLargeInteger& divBy) {
for (NLargeInteger* x = this->data[row];
x != this->data[row] + nCols; ++x)
x->divByExact(divBy);
}
/**
* Divides all elements of the given column by the given integer.
* This can only be used when the given integer divides into all
* column elements exactly (with no remainder), and is much faster
* than ordinary division.
*
* \pre The argument \a divBy is neither zero nor infinity, and
* none of the elements of the given column are infinity.
* \pre The argument \a divBy divides exactly into every element
* of the given column (i.e., it leaves no remainder).
* \pre The given column number is between 0 and columns()-1 inclusive.
*
* @param col the index of the column whose elements should be
* divided by \a divBy.
* @param divBy the integer to divide each column element by.
*/
void divColExact(unsigned long col, const NLargeInteger& divBy) {
for (NLargeInteger** row = this->data; row != this->data + nRows;
++row)
(*row)[col].divByExact(divBy);
}
/**
* Computes the greatest common divisor of all elements of the
* given row. The value returned is guaranteed to be non-negative.
*
* \pre The given row number is between 0 and rows()-1 inclusive.
*
* @param row the index of the row whose gcd should be computed.
* @return the greatest common divisor of all elements of this row.
*/
NLargeInteger gcdRow(unsigned long row) {
NLargeInteger* x = this->data[row];
NLargeInteger gcd = *x++;
while (x != this->data[row] + nCols && gcd != 1 && gcd != -1)
gcd = gcd.gcd(*x++);
if (gcd < 0)
gcd.negate();
return gcd;
}
/**
* Computes the greatest common divisor of all elements of the
* given column. The value returned is guaranteed to be non-negative.
*
* \pre The given column number is between 0 and columns()-1 inclusive.
*
* @param col the index of the column whose gcd should be computed.
* @return the greatest common divisor of all elements of this column.
*/
NLargeInteger gcdCol(unsigned long col) {
NLargeInteger** row = this->data;
NLargeInteger gcd = (*row++)[col];
while (row != this->data + nRows && gcd != 1 && gcd != -1)
gcd = gcd.gcd((*row++)[col]);
if (gcd < 0)
gcd.negate();
return gcd;
}
/**
* Reduces the given row by dividing all its elements by their
* greatest common divisor. It is guaranteed that, if the row is
* changed at all, it will be divided by a \e positive integer.
*
* \pre The given row number is between 0 and rows()-1 inclusive.
*
* @param row the index of the row to reduce.
*/
void reduceRow(unsigned long row) {
NLargeInteger gcd = gcdRow(row);
if (gcd != NLargeInteger::zero && gcd != NLargeInteger::one)
divRowExact(row, gcd);
}
/**
* Reduces the given column by dividing all its elements by their
* greatest common divisor. It is guaranteed that, if the column is
* changed at all, it will be divided by a \e positive integer.
*
* \pre The given column number is between 0 and columns()-1 inclusive.
*
* @param col the index of the column to reduce.
*/
void reduceCol(unsigned long col) {
NLargeInteger gcd = gcdCol(col);
if (gcd != NLargeInteger::zero && gcd != NLargeInteger::one)
divColExact(col, gcd);
}
virtual void writeTextShort(std::ostream& out) const;
virtual void writeTextLong(std::ostream& out) const;
};
// Inline functions for NMatrixInt
inline NMatrixInt::NMatrixInt(unsigned long rows, unsigned long cols) :
NMatrixRing<NLargeInteger>(rows, cols), ShareableObject() {
}
inline NMatrixInt::NMatrixInt(const NMatrixInt& cloneMe) :
NMatrixRing<NLargeInteger>(cloneMe), ShareableObject() {
}
inline void NMatrixInt::writeTextShort(std::ostream& out) const {
out << nRows << " x " << nCols << " integer matrix";
}
inline void NMatrixInt::writeTextLong(std::ostream& out) const {
writeMatrix(out);
}
/*@}*/
} // namespace regina
#endif
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