/usr/include/linbox/util/field-axpy.h is in liblinbox-dev 1.3.2-1.1+b1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 | /* linbox/util/field-axpy.h
* Copyright (C) 1999-2001 William J Turner,
* 2001 Bradford Hovinen
*
* Written by William J Turner <wjturner@math.ncsu.edu>,
* Bradford Hovinen <hovinen@cis.udel.edu>
*
* ========LICENCE========
* This file is part of the library LinBox.
*
* LinBox is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
* ========LICENCE========
*/
#ifndef __LINBOX_util_field_axpy_H
#define __LINBOX_util_field_axpy_H
// Namespace in which all LinBox library code resides
namespace LinBox
{
/** FieldAXPY object.
*
* This class is used to wrap the operation <code>y = y + a * x</code>. It acts as an
* accumulator for \c y.
*
* Through the use of template specialization, objects of this type can
* be used to speed up vector dot product operations. In particular, for
* finite fields, dividing by the modulus and taking the remainder is
* expensive. In many cases, this can be postponed until the end of the
* dot product operation, thus vastly improving performance.
*
* This object is constructed from the field object \c F and a field
* element a which it stores and thus can use several times. The use of
* an object instead of a static variable to store the element a makes
* this method thread-safe.
*
* @param Field \ref LinBox @link Fields field@endlink
*/
template <class Field>
class FieldAXPY {
public:
/// Definition of element type
typedef typename Field::Element Element;
/** Constructor.
* A faxpy object if constructed from a Field and a field element.
* Copies of this objects are stored in the faxpy object.
* @param F field F in which arithmetic is done
*/
FieldAXPY (const Field &F) :
_field (F)
{ _field.init (_y, 0); }
/** Copy constructor.
* @param faxpy
*/
FieldAXPY (const FieldAXPY<Field> &faxpy) :
_field (faxpy._field), _y (faxpy._y)
{}
/** Assignment operator
* @param faxpy
*/
FieldAXPY<Field> &operator = (const FieldAXPY &faxpy)
{ _y = faxpy._y; return *this; }
/** Add a*x to y
* y += a*x.
* @param a constant reference to element a
* @param x constant reference to element x
*/
inline Element& mulacc (const Element &a, const Element &x)
{ return _field.axpyin (_y, a, x); }
inline Element& accumulate (const Element &t)
{ return _field.addin (_y, t); }
/** Retrieve y
*
* Performs the delayed modding out if necessary
*/
inline Element &get (Element &y) { y = _y; return y; }
/** Assign method.
* Stores new field element for arithmetic.
* @return reference to self
* @param y constant reference to element a
*/
inline FieldAXPY &assign (const Element y)
{
_y = y;
return *this;
}
inline void reset() {
_field.init(_y,0);
}
protected:
/// Field in which arithmetic is done
/// Not sure why it must be mutable, but the compiler complains otherwise
Field _field;
/// Field element for arithmetic
Element _y;
}; // class FieldAXPY
} // namespace LinBox
#endif // __LINBOX_util_field_axpy_H
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