global etype a[a_size]

procedure find_seq_max() 

  returns etype max

  int i = lb(a) + 1
  max = a[i - 1]

  while (i <= ub(a))
    if (a[i] > max)
      max = a[i]
    i++

global etype a[a_size];

procedure find_half_max(int start) 

  returns etype max

  max = a[start]
  int i = start + 2;

  while (i <= ub(a))
    if (a[i] > max)
      max = a[i]
    i += 2

procedure find_par_max() 

  returns etype mx

  etype odd_max, even_max

  co
     odd_max = find_half_max(lb(a))
  ||
     even_max = find_half_max(lb(a) + 1)
  oc

  mx = max(odd_max, even_max)

procedure time_par(int iters) {

  # Time the parallel array max.

  int stime = age()
  for [i = 1 to iters] {
    }
  const int otime = (age() - stime);

  stime = age()
  for [i = 1 to iters] {
    find_par_max();
    }
  const int etime = (age() - stime) - otime;

  printf("parallel %d elements %4.1f ms/call.\n",
	 a_size, real(etime)/real(iters))
  }

double a[1:a_size]
double a_max
sem mutex = 1

procedure find_global_half_max(int start)

  int i = start;

  while (i <= ub(a))
    P(mutex)
    if (a[i] > a_max)
      a_max = a[i]
    V(mutex)
    i += 2

procedure find_seqpar_max()

  const int i = lb(a)
  a_max = a[i]

  co
     find_global_half_max(i)
  ||
     find_global_half_max(i + 1)
  oc