isortq, ssortq, dsortq 

Sort the elements of a vector

FORMAT

  {I,S,D}SORTQ

  ( order, n, x, incx )

Arguments

  order               character*1
                      On entry, order specifies the operation to be performed
                      as follows:

                      If order = 'A' or 'a', x is sorted in ascending
                      sequence

                      If order = 'D' or 'd', x is sorted in descending
                      sequence
                      On exit, order is unchanged.

  n                   integer*4
                      On entry, the length of vector x.
                      On exit, n is unchanged.

  x                   integer*4 | real*4 | real*8
                      On entry, a length n vector of data to be sorted.
                      On exit, x is overwritten by a length n vector of
                      sorted data.

  incx                integer*4
                      On entry, incx specifies the distance between elements
                      of vector x. incx must be positive.
                      On exit, incx is unchanged.

Description

  The _SORTQ routines sort a vector of data using the quicksort algorithm.
  Data is sorted in ascending order if order is 'A' or 'a' and in descending
  order if order is 'D' or 'd'. The quicksort algorithm is implemented by
  recursing until the partition size is less than sixteen. At that point a
  simple replacement sort is used to sort the elements of the partition.

Example

  REAL*4 DATA( 100 )
  N = 100
  CALL SSORTQ( 'A',N,DATA,1 )

  This FORTRAN code sorts a 100 element single real vector.