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// Copyright (C) 2003--2004 Zbigniew Leyk (zbigniew.leyk@anu.edu.au)
// and David E. Stewart (david.stewart@anu.edu.au)
// and Ronan Collobert (collober@idiap.ch)
//
// This file is part of Torch 3.1.
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// 3. The name of the author may not be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
// IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
// NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "mx_givens.h"
namespace Torch {
/*
Files for matrix computations
Givens operations file. Contains routines for calculating and
applying givens rotations for/to vectors and also to matrices by
row and by column.
*/
/* givens -- returns c,s parameters for Givens rotation to
eliminate y in the vector [ x y ]' */
void mx_givens(real x, real y, real * c, real * s)
{
real norm = sqrt(x * x + y * y);
if (norm == 0.0)
{
*c = 1.0;
*s = 0.0;
} /* identity */
else
{
*c = x / norm;
*s = y / norm;
}
}
/* rot_vec -- apply Givens rotation to x's i & k components */
void mx_rot_vec(Vec * x, int i, int k, real c, real s, Vec * out)
{
out->copy(x);
real temp = c * out->ptr[i] + s * out->ptr[k];
out->ptr[k] = -s * out->ptr[i] + c * out->ptr[k];
out->ptr[i] = temp;
}
/* rot_rows -- premultiply mat by givens rotation described by c,s */
void mx_rot_rows(Mat * mat, int i, int k, real c, real s, Mat * out)
{
out->copy(mat);
for (int j = 0; j < mat->n; j++)
{
real temp = c * out->ptr[i][j] + s * out->ptr[k][j];
out->ptr[k][j] = -s * out->ptr[i][j] + c * out->ptr[k][j];
out->ptr[i][j] = temp;
}
}
/* rot_cols -- postmultiply mat by givens rotation described by c,s */
void mx_rot_cols(Mat * mat, int i, int k, real c, real s, Mat * out)
{
out->copy(mat);
for (int j = 0; j < mat->m; j++)
{
real temp = c * out->ptr[j][i] + s * out->ptr[j][k];
out->ptr[j][k] = -s * out->ptr[j][i] + c * out->ptr[j][k];
out->ptr[j][i] = temp;
}
}
}
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