# Two quantile utilities.  Changed since formally tested.
#
# value = value of bb(k) if bb(1...n) were sorted into increasing order.
subroutine quantile( k, n, bb, value)
	integer   i, k, n; 	real bb(n), value
	temporary real aa(n)
	do i= 1, n
		aa(i) = bb(i)
	call quantinternal( k, n, aa)
	value = aa(k)
	return; end

# value = value of abs(bb(k)) if abs(bb(1...n)) were sorted to increasing order.
subroutine quantabs( k, n, bb, value)
	integer   i, k, n;	real bb(n), value
	temporary real aa(n)
	do i= 1, n
		aa(i) = abs( bb(i))
	call quantinternal( k, n, aa)
	value = aa(k)
	return; end

subroutine quantinternal( k, n, a)
integer k, n;			real a(n)
integer i, j, low, hi;		real ak, aa
if( k>n | k<1)  call erexit("quant: inputs not in range  1 <= k <= n ")
low = 1;	hi = n
while( low < hi) {
	ak = a(k);	i = low;	j = hi
	repeat {
		if( a(i) < ak)
			i = i+1
		else {
			while( a(j) > ak)	j = j-1
			if( i > j)  break 1
			aa = a(i);	a(i) = a(j);	a(j) = aa
			i = i+1; 	j = j-1
			if( i > j)  break 1
			}
		}
	if( j < k)  low = i
	if( k < i)  hi = j
	}
return; end