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===== Dotprod =====

<code c++ dotprod.cpp>
/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* ***************************************************************************
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as 
 *  published by the Free Software Foundation.
 *
 *  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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 *  As a special exception, you may use this file as part of a free software
 *  library without restriction.  Specifically, if other files instantiate
 *  templates or use macros or inline functions from this file, or you compile
 *  this file and link it with other files to produce an executable, this
 *  file does not by itself cause the resulting executable to be covered by
 *  the GNU General Public License.  This exception does not however
 *  invalidate any other reasons why the executable file might be covered by
 *  the GNU General Public License.
 *
 ****************************************************************************
 */

#include <ff/parallel_for.hpp>

using namespace ff;

int main(int argc, char * argv[]) {    
    if (argc<3) {
        printf("use: %s arraysize nworkers [ntimes] [CHUNKSIZE]\n", argv[0]);
        return -1;
    }
    int arraySize= atoi(argv[1]);
    int nworkers = atoi(argv[2]);
    int NTIMES   = 1;
    int CHUNKSIZE= std::min(10000, arraySize/nworkers);

    if (argc>=4) NTIMES = atoi(argv[3]);
    if (argc==5) CHUNKSIZE = atoi(argv[4]);

    if (nworkers<=0) {
        printf("Wrong parameters values\n");
        return -1;
    }
    
    // creates the array
    double *A = new double[arraySize];
    double *B = new double[arraySize];

    double sum = 5.0;

    FF_PARFORREDUCE_INIT(dp, double, nworkers);

    // init data
    FF_PARFOR_BEGIN(init, j,0,arraySize,1, CHUNKSIZE, nworkers) {
        A[j]=j*3.14; B[j]=2.1*j;
    } FF_PARFOR_END(init);
        
    ff::ffTime(ff::START_TIME);    
    for(int z=0;z<NTIMES;++z) {
        // do work
        FF_PARFORREDUCE_START(dp, sum, 0.0, i,0,arraySize,1, CHUNKSIZE, nworkers) { 
            sum += A[i]*B[i];
        } FF_PARFORREDUCE_STOP(dp, sum, +);    
    }
    ffTime(STOP_TIME);
    FF_PARFORREDUCE_DONE(dp);
    printf("ff %d Time = %g ntimes=%d\n", nworkers, ffTime(GET_TIME), NTIMES);
    printf("Sum =%g\n", sum);
    return 0;
}
</code>