• NAME
• SYNOPSIS
• F95 INTERFACE
• C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

zgebak - form the right or left eigenvectors of a complex general matrix by backward transformation on the computed eigenvectors of the balanced matrix output by CGEBAL

SYNOPSIS

  SUBROUTINE ZGEBAK( JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV, INFO)
  CHARACTER * 1 JOB, SIDE
  DOUBLE COMPLEX V(LDV,*)
  INTEGER N, ILO, IHI, M, LDV, INFO
  DOUBLE PRECISION SCALE(*)

  SUBROUTINE ZGEBAK_64( JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV, 
 *      INFO)
  CHARACTER * 1 JOB, SIDE
  DOUBLE COMPLEX V(LDV,*)
  INTEGER*8 N, ILO, IHI, M, LDV, INFO
  DOUBLE PRECISION SCALE(*)

F95 INTERFACE

  SUBROUTINE GEBAK( JOB, SIDE, [N], ILO, IHI, SCALE, [M], V, [LDV], 
 *       [INFO])
  CHARACTER(LEN=1) :: JOB, SIDE
  COMPLEX(8), DIMENSION(:,:) :: V
  INTEGER :: N, ILO, IHI, M, LDV, INFO
  REAL(8), DIMENSION(:) :: SCALE

  SUBROUTINE GEBAK_64( JOB, SIDE, [N], ILO, IHI, SCALE, [M], V, [LDV], 
 *       [INFO])
  CHARACTER(LEN=1) :: JOB, SIDE
  COMPLEX(8), DIMENSION(:,:) :: V
  INTEGER(8) :: N, ILO, IHI, M, LDV, INFO
  REAL(8), DIMENSION(:) :: SCALE

C INTERFACE

#include <sunperf.h>

void zgebak(char job, char side, int n, int ilo, int ihi, double *scale, int m, doublecomplex *v, int ldv, int *info);

void zgebak_64(char job, char side, long n, long ilo, long ihi, double *scale, long m, doublecomplex *v, long ldv, long *info);

PURPOSE

zgebak forms the right or left eigenvectors of a complex general matrix by backward transformation on the computed eigenvectors of the balanced matrix output by CGEBAL.

ARGUMENTS

• JOB (input)
  Specifies the type of backward transformation required: = 'N', do nothing, return immediately; = 'P', do backward transformation for permutation only; = 'S', do backward transformation for scaling only; = 'B', do backward transformations for both permutation and scaling. JOB must be the same as the argument JOB supplied to CGEBAL.

• SIDE (input)
  

   = 'R':  V contains right eigenvectors;

   = 'L':  V contains left eigenvectors.

• N (input)
  The number of rows of the matrix V. N > = 0.

• ILO (input)
  The integer ILO determined by CGEBAL. 1 < = ILO < = IHI < = N, if N > 0; ILO =1 and IHI =0, if N =0.

• IHI (input)
  The integer IHI determined by CGEBAL. 1 < = ILO < = IHI < = N, if N > 0; ILO =1 and IHI =0, if N =0.

• SCALE (input)
  Details of the permutation and scaling factors, as returned by CGEBAL.

• M (input)
  The number of columns of the matrix V. M > = 0.

• V (input/output)
  On entry, the matrix of right or left eigenvectors to be transformed, as returned by CHSEIN or CTREVC. On exit, V is overwritten by the transformed eigenvectors.

• LDV (input)
  The leading dimension of the array V. LDV > = max(1,N).

• INFO (output)
  

   = 0:  successful exit

   < 0:  if INFO  = -i, the i-th argument had an illegal value.