SYNOPSIS
 SUBROUTINE SLASRT2(
 ID, N, D, KEY, INFO )
 CHARACTER ID
 INTEGER INFO, N
 INTEGER KEY( * )
 REAL D( * )
PURPOSE
Sort the numbers in D in increasing order (if ID = 'I') or in decreasing order (if ID = 'D' ).
Use Quick Sort, reverting to Insertion sort on arrays of
size <= 20. Dimension of STACK limits N to about 2**32.
ARGUMENTS
 ID (input) CHARACTER*1

= 'I': sort D in increasing order;
= 'D': sort D in decreasing order.  N (input) INTEGER
 The length of the array D.
 D (input/output) REAL array, dimension (N)
 On entry, the array to be sorted. On exit, D has been sorted into increasing order (D(1) <= ... <= D(N) ) or into decreasing order (D(1) >= ... >= D(N) ), depending on ID.
 KEY (input/output) INTEGER array, dimension (N)
 On entry, KEY contains a key to each of the entries in D() Typically, KEY(I) = I for all I On exit, KEY is permuted in exactly the same manner as D() was permuted from input to output Therefore, if KEY(I) = I for all I upon input, then D_out(I) = D_in(KEY(I))
 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value