/* blas/source_nrm2_r.h * * Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman * * 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 3 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 Street, Fifth Floor, Boston, MA 02110-1301, USA. */ { BASE scale = 0.0; BASE ssq = 1.0; INDEX i; INDEX ix = 0; if (N <= 0 || incX <= 0) { return 0; } else if (N == 1) { return fabs(X[0]); } for (i = 0; i < N; i++) { const BASE x = X[ix]; if (x != 0.0) { const BASE ax = fabs(x); if (scale < ax) { ssq = 1.0 + ssq * (scale / ax) * (scale / ax); scale = ax; } else { ssq += (ax / scale) * (ax / scale); } } ix += incX; } return scale * sqrt(ssq); }

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