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/* ---------------------------------------------------------------------
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* -- Automatically Tuned Linear Algebra Software (ATLAS)
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* (C) Copyright 2000 All Rights Reserved
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* -- ATLAS routine -- Version 3.2 -- December 15, 2000
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* -- Suggestions, comments, bugs reports should be sent to the follo-
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* wing e-mail address: atlas@cs.utk.edu
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* Author : Antoine P. Petitet
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* University of Tennessee - Innovative Computing Laboratory
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* Knoxville TN, 37996-1301, USA.
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* ---------------------------------------------------------------------
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* -- Copyright notice and Licensing terms:
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions, and the following disclaimer in
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* the documentation and/or other materials provided with the distri-
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* 3. The name of the University, the ATLAS group, or the names of its
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* contributors may not be used to endorse or promote products deri-
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* ved from this software without specific written permission.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY
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* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
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* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
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* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEO-
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* RY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (IN-
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* CLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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* ---------------------------------------------------------------------
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#include "atlas_refmisc.h"
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#include "atlas_reflevel1.h"
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* ATL_drefnrm2 returns the 2-norm of an n-vector x.
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* On entry, N specifies the length of the vector x. N must be
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* at least zero. Unchanged on exit.
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* X (input) const double *
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* On entry, X points to the first entry to be accessed of an
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* incremented array of size equal to or greater than
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* ( 1 + ( n - 1 ) * abs( INCX ) ) * sizeof( double ),
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* that contains the vector x. Unchanged on exit.
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* INCX (input) const int
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* On entry, INCX specifies the increment for the elements of X.
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* INCX must not be zero. Unchanged on exit.
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* ---------------------------------------------------------------------
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* .. Local Variables ..
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register double absxi, scale = ATL_dZERO,
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ssq = ATL_dONE, temp, x0, x1, x2, x3, x4,
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double * StX = (double *)(X) + N * INCX;
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const int incX2 = 2 * INCX, incX3 = 3 * INCX,
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incX4 = 4 * INCX, incX5 = 5 * INCX,
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incX6 = 6 * INCX, incX7 = 7 * INCX,
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* .. Executable Statements ..
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if( ( N < 1 ) || ( INCX < 1 ) ) return( ATL_dZERO );
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else if( N == 1 ) return( Mdabs( *X ) );
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while( ( *X == ATL_dZERO ) && ( X != StX ) ) { X += INCX; n--; }
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if( X == StX ) return( ATL_dZERO );
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if( ( nu = ( n >> 3 ) << 3 ) != 0 )
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StX = (double *)X + nu * INCX;
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x0 = (*X); x4 = X[incX4]; x1 = X[INCX ]; x5 = X[incX5];
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x2 = X[incX2]; x6 = X[incX6]; x3 = X[incX3]; x7 = X[incX7];
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temp = scale / absxi; scale = absxi;
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ssq = ATL_dONE + ssq * ( temp * temp );
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else { temp = absxi / scale; ssq += temp * temp; }
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temp = scale / absxi; scale = absxi;
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ssq = ATL_dONE + ssq * ( temp * temp );
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else { temp = absxi / scale; ssq += temp * temp; }
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temp = scale / absxi; scale = absxi;
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ssq = ATL_dONE + ssq * ( temp * temp );
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else { temp = absxi / scale; ssq += temp * temp; }
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temp = scale / absxi; scale = absxi;
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ssq = ATL_dONE + ssq * ( temp * temp );
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else { temp = absxi / scale; ssq += temp * temp; }
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temp = scale / absxi; scale = absxi;
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ssq = ATL_dONE + ssq * ( temp * temp );
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else { temp = absxi / scale; ssq += temp * temp; }
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temp = scale / absxi; scale = absxi;
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ssq = ATL_dONE + ssq * ( temp * temp );
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else { temp = absxi / scale; ssq += temp * temp; }
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temp = scale / absxi; scale = absxi;
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ssq = ATL_dONE + ssq * ( temp * temp );
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else { temp = absxi / scale; ssq += temp * temp; }
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temp = scale / absxi; scale = absxi;
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ssq = ATL_dONE + ssq * ( temp * temp );
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else { temp = absxi / scale; ssq += temp * temp; }
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for( i = n - nu; i != 0; i-- )
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temp = scale / absxi; scale = absxi;
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ssq = ATL_dONE + ssq * ( temp * temp );
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else { temp = absxi / scale; ssq += temp * temp; }
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return( scale * sqrt( ssq ) );
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* End of ATL_drefnrm2
added
removed
src/blas/reference/level1/ATL_drefnrm2.c
