source_axpy_r.h

开放gsl矩阵运算

/* blas/source_axpy_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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

{
  INDEX i;

  if (alpha == 0.0) {
    return;
  }

  if (incX == 1 && incY == 1) {
    const INDEX m = N % 4;

    for (i = 0; i < m; i++) {
      Y[i] += alpha * X[i];
    }

    for (i = m; i + 3 < N; i += 4) {
      Y[i] += alpha * X[i];
      Y[i + 1] += alpha * X[i + 1];
      Y[i + 2] += alpha * X[i + 2];
      Y[i + 3] += alpha * X[i + 3];
    }
  } else {
    INDEX ix = OFFSET(N, incX);
    INDEX iy = OFFSET(N, incY);

    for (i = 0; i < N; i++) {
      Y[iy] += alpha * X[ix];
      ix += incX;
      iy += incY;
    }
  }
}