SLATEC Routines --- ISWAP ---

*DECK ISWAP
      SUBROUTINE ISWAP (N, IX, INCX, IY, INCY)
C***BEGIN PROLOGUE  ISWAP
C***PURPOSE  Interchange two vectors.
C***LIBRARY   SLATEC (BLAS)
C***CATEGORY  D1A5
C***TYPE      INTEGER (SSWAP-S, DSWAP-D, CSWAP-C, ISWAP-I)
C***KEYWORDS  BLAS, INTERCHANGE, LINEAR ALGEBRA, VECTOR
C***AUTHOR  Vandevender, W. H., (SNLA)
C***DESCRIPTION
C
C                Extended B L A S  Subprogram
C    Description of Parameters
C
C     --Input--
C        N  number of elements in input vector(s)
C       IX  integer vector with N elements
C     INCX  storage spacing between elements of IX
C       IY  integer vector with N elements
C     INCY  storage spacing between elements of IY
C
C     --Output--
C       IX  input vector IY (unchanged if N .LE. 0)
C       IY  input vector IX (unchanged if N .LE. 0)
C
C     Interchange integer IX and integer IY.
C     For I = 0 to N-1, interchange  IX(LX+I*INCX) and IY(LY+I*INCY),
C     where LX = 1 if INCX .GE. 0, else LX = 1+(1-N)*INCX, and LY is
C     defined in a similar way using INCY.
C
C***REFERENCES  C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T.
C                 Krogh, Basic linear algebra subprograms for Fortran
C                 usage, Algorithm No. 539, Transactions on Mathematical
C                 Software 5, 3 (September 1979), pp. 308-323.
C***ROUTINES CALLED  (NONE)
C***REVISION HISTORY  (YYMMDD)
C   850601  DATE WRITTEN
C   861211  REVISION DATE from Version 3.2
C   891214  Prologue converted to Version 4.0 format.  (BAB)
C   920310  Corrected definition of LX in DESCRIPTION.  (WRB)
C   920501  Reformatted the REFERENCES section.  (WRB)
C***END PROLOGUE  ISWAP