CORTB(3F)

NAME
     CORTB, SCORTB   -  EISPACK routine.  This subroutine forms the
     eigenvectors of a COMPLEX GENERAL matrix by back transforming those of
     the corresponding upper Hessenberg matrix determined by  CORTH.


SYNOPSYS
          subroutine  cortb(nm, low, igh, ar, ai, ortr, orti, m, zr, zi)
          integer          nm, low, igh, m
          double precision ar(nm,igh), ai(nm,igh), ortr(igh), orti(igh)
          double precision zr(nm,m),   zi(nm,m)

          subroutine scortb(nm, low, igh, ar, ai, ortr, orti, m, zr, zi)
          integer          nm, low, igh, m
          real             ar(nm,igh), ai(nm,igh), ortr(igh), orti(igh)
          real             zr(nm,m),   zi(nm,m)



DESCRIPTION
     On INPUT

     NM must be set to the row dimension of two-dimensional array parameters
     as declared in the calling program dimension statement.

     LOW and IGH are integers determined by the balancing subroutine  CBAL.
     If  CBAL  has not been used, set LOW=1 and IGH equal to the order of the
     matrix.

     AR and AI contain information about the unitary transformations used in
     the reduction by  CORTH in their strict lower triangles.

     ORTR and ORTI contain further information about the transformations used
     in the reduction by  CORTH.  Only elements LOW through IGH are used.

     M is the number of columns of ZR and ZI to be back transformed.

     ZR and ZI contain the real and imaginary parts, respectively, of the
     eigenvectors to be back transformed in their first M columns.  On OUTPUT

     ZR and ZI contain the real and imaginary parts, respectively, of the
     transformed eigenvectors in their first M columns.

     ORTR and ORTI have been altered. Note that CORTB preserves vector
     Euclidean norms.  Questions and comments should be directed to B. S.
     Garbow, APPLIED MATHEMATICS DIVISION, ARGONNE NATIONAL LABORATORY