CSCI 3366
Spring 2004
Homework Three
           
Continuing our discussion of divide and conquer algorithms, we will write
a C-MPI program which will perform a simple parallel sort. The master 
process will generate an array of a given size (command line) of random
numbers to be sorted. Depending on the number of processors available, 
the array will be divided among the processors so that each has an equal
share to sort. You may use an ordinary bubble sort (since we wish to make
the processors work hard in order to gain some benefit from parallelism).
The processors will sort their chunk of the array, and pass the sorted 
array back to the master process, who will display the sorted results.  

This all sounds pretty familiar doesn't it? The only catch in this code is
that you must use collective communication tools discussed in class to 
accomplish the task. Take timings of your code using the simple send
and receive commands, and compare with the times you obtain by using
the collective communication tools and see if any improvement in time
is achieved. Do several comparisons. 

Make sure you set the permissions on your source so I can read your 
programs. 

Homework due Tuesday, February 7, 2004

int Bubble(int *a, int n)
{	int 
		notstop, 
		i;
	notstop = 1;
	while (notstop == 1)
	{	notstop = 0;
		for (i=0; i<n-1; i++)
		{	if (a[i] > a[i+1])
			{	int t;
				t = a[i]; a[i] = a[i+1]; a[i+1] = t;
				notstop = 1;
			}
		}
		n--;
	}
}