# include <stdlib.h>
# include <stdio.h>
# include <math.h>
# include <time.h>
# include <omp.h>

int main ( int argc, char *argv[] );

/******************************************************************************/

int main ( int argc, char *argv[] )

/******************************************************************************/
/*
  Purpose:

    MAIN is the main program for L1_NORM.
*/
{
  int i;
  int j;
  int num_threads;
  int n = 1000;
  double wtime;
  double wtime1;
  double wtime2;
  float *x;
  float *x_l1_norm;

# pragma omp parallel
{
  num_threads = omp_get_num_threads ( );
}
  printf ( "\n" );
  printf ( "L1_NORM:\n" );
  printf ( "  C version\n" );
  printf ( "  Number of threads is %d\n", num_threads );

  x = ( float * ) malloc ( n * n * sizeof ( float ) );
/*
  Set X to random values.
*/
  for ( j = 0; j < n; j++ )
  {
    for ( i = 0; i < n; i++ )
    {
      x[i+j*n] =  ( float ) rand ( ) / ( float ) RAND_MAX;
    }
  }

  x_l1_norm = ( float * ) malloc ( n * sizeof ( float ) );
/*
  Compute the l1 norm sequentially.
*/
  wtime1 = omp_get_wtime ( );
  for ( j = 0; j < n; j++ )
  {
    x_l1_norm[j] = 0.0;
    for ( i = 0; i < n; i++ )
    {
      x_l1_norm[j] = x_l1_norm[j] + fabs ( x[i+j*n] );
    }
  }
  wtime2 = omp_get_wtime ( );
  wtime = wtime2 - wtime1;

  printf ( "\n" );
  printf ( "Sequential calculation:\n" );
  printf ( "  L1_NORM (first 4 ) = %f\n", x_l1_norm[0], x_l1_norm[1], x_l1_norm[2], x_l1_norm[3] );
  printf ( "  Time =    %f\n", wtime );
/*
  Compute the l1 norm in parallel.
*/
  wtime1 = omp_get_wtime ( );
# pragma omp parallel private ( i, j ) shared ( n, x, x_l1_norm )
# pragma omp for
  for ( j = 0; j < n; j++ )
  {
    x_l1_norm[j] = 0.0;
    for ( i = 0; i < n; i++ )
    {
      x_l1_norm[j] = x_l1_norm[j] + fabs ( x[i+j*n] );
    }
  }
  wtime2 = omp_get_wtime ( );
  wtime = wtime2 - wtime1;

  printf ( "\n" );
  printf ( "Parallel calculation:\n" );
  printf ( "  L1_NORM (first 4 ) = %f\n", x_l1_norm[0], x_l1_norm[1], x_l1_norm[2], x_l1_norm[3] );
  printf ( "  Time =    %f\n", wtime );

  free ( x );
  free ( x_l1_norm );

  return 0;
}