Sorting program that uses a quicksort algorithm. Applies for an input array of Real(KIND=8) values which is reordered. It also returns an array of indexes sorted for increasing order of X. You can use GR8_SORT to reorder other arrays associated with X.
Arguments :
X R*8(*) Unsorted/Sorted array Input/Output
INDEX I(*) Integer array of sorted indexes Output
N I Length of arrays Input
* Label Error return