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


#define N 100
#define NZ 200

int main(int argc, char *argv[]) {
  double x[N], y[N], a[NZ], b[N], d, xmax;
  int row[NZ], col[NZ], i, j, k, imax;
  for (k=0;k<NZ; k++) {
    a[k] = sin(2.0*i);
    row[k]= k%50;
    col[k]= 25 + k%24;
  }
  for ( i=0; i<N; i++ ) {
    x[i]=sin(1.1*i)/(1.0+i);
    b[i]= 1-x[i];
  }

  // Ex 3.1:

  d = 0.0;
#pragma omp parallel for private (i,j) reduction (+:d)
  for ( k=0; k < NZ; k++ ) {
    i = row[k];
    j = col[k];
    d = d + a[k]*x[i]*x[j];
  }

  // Ex 3.2:

  a[0] = 1 ; b[0] = 2 ;
#pragma omp parallel sections private (i)
  {
#pragma section
  for ( i=0; i < N-1; i++ ) 
    a[i+1] = a[i] + sin( a[i] );
#pragma section
  for ( i=0; i < N-1; i++ ) 
    b[i+1] = b[i] + cos( b[i] );
  }

  // Ex 3.5


  xmax = x[0];
  imax = 0;
#pragma omp parallel for
  for ( i=0; i<N; i++ ) {
    if ( x[i] > xmax ) {
#pragma omp critical
      {
	if ( x[i] > xmax ) {
	  xmax = x[i];
	  imax = i;
	}
      }
    }
  }
  printf("Max. value x[%d] = %lf\n",imax,xmax);
}