01        SUBROUTINE SLASRT2( ID , N , D , KEY , INFO )
02  
03  *     -- ScaLAPACK routine(version 1.7) --
04  *     University of Tennessee , Knoxville , Oak Ridge National Laboratory ,
05  *     and University of California , Berkeley.
06  *     May 1 , 1997
07  
08  *     .. Scalar Arguments ..
09        CHARACTER ID
10        INTEGER INFO , N
11  *     ..
12  *     .. Array Arguments ..
13        INTEGER KEY( * )
14        REAL D( * )
15  *     ..
16  
17  *     Purpose
18  *     === ====
19  
20  *     Sort the numbers in D in increasing order(if ID = 'I') or
21  *     in decreasing order(if ID = 'D' ).
22  
23  *     Use Quick Sort , reverting to Insertion sort on arrays of
24  *     size <= 20. Dimension of STACK limits N to about 2**32.
25  
26  *     Arguments
27  *     === ======
28  
29  *     ID(input) CHARACTER*1
30  *     = 'I' : sort D in increasing order ;
31  *     = 'D' : sort D in decreasing order.
32  
33  *     N(input) INTEGER
34  *     The length of the array D.
35  
36  *     D(input / output) REAL array , dimension(N)
37  *     On entry , the array to be sorted.
38  *     On exit , D has been sorted into increasing order
39  *     (D(1) <= ... <= D(N) ) or into decreasing order
40  *     (D(1) >= ... >= D(N) ) , depending on ID.
41  
42  *     KEY(input / output) INTEGER array , dimension(N)
43  *     On entry , KEY contains a key to each of the entries in D()
44  *     Typically , KEY(I) = I for all I
45  *     On exit , KEY is permuted in exactly the same manner as
46  *     D() was permuted from input to output
47  *     Therefore , if KEY(I) = I for all I upon input , then
48  *     D_out(I) = D_in(KEY(I))
49  
50  *     INFO(output) INTEGER
51  *     = 0 : successful exit
52  *     < 0 : if INFO = - i , the i - th argument had an illegal value
53  
54  *     === ==================================================================
55  
56  *     .. Parameters ..
57        INTEGER SELECT
58        PARAMETER( SELECT = 20 )
59        END3813