******** fig7.13 **********

	/* Return median of left, center, and right.  Order these and hide pivot */

	input_type
	median3( input_type a[], int left, int right )
	{
		int center;

		center = (left + right) / 2;

		if( a[left] > a[center] )
			swap( &a[left], &a[center] );
		if( a[left] > a[right] )
			swap( &a[left], &a[right] );
		if( a[center] > a[right] )
			swap( &a[center], &a[right] );

		/* invariant: a[left] <= a[center] <= a[right] */

		swap( &a[center], &a[right-1] );	/* hide pivot */
		return a[right-1];			/* return pivot */
	}