| /* 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 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 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); |
| } |
