NAME

SYNOPSIS

  SUBROUTINE CTREVC( SIDE, HOWMNY, SELECT, N, T, LDT, VL, LDVL, VR, 
 *      LDVR, MM, M, WORK, RWORK, INFO)
  CHARACTER * 1 SIDE, HOWMNY
  COMPLEX T(LDT,*), VL(LDVL,*), VR(LDVR,*), WORK(*)
  INTEGER N, LDT, LDVL, LDVR, MM, M, INFO
  LOGICAL SELECT(*)
  REAL RWORK(*)
 
  SUBROUTINE CTREVC_64( SIDE, HOWMNY, SELECT, N, T, LDT, VL, LDVL, VR, 
 *      LDVR, MM, M, WORK, RWORK, INFO)
  CHARACTER * 1 SIDE, HOWMNY
  COMPLEX T(LDT,*), VL(LDVL,*), VR(LDVR,*), WORK(*)
  INTEGER*8 N, LDT, LDVL, LDVR, MM, M, INFO
  LOGICAL*8 SELECT(*)
  REAL RWORK(*)
 

F95 INTERFACE

  SUBROUTINE TREVC( SIDE, HOWMNY, SELECT, [N], T, [LDT], VL, [LDVL], 
 *       VR, [LDVR], MM, M, [WORK], [RWORK], [INFO])
  CHARACTER(LEN=1) :: SIDE, HOWMNY
  COMPLEX, DIMENSION(:) :: WORK
  COMPLEX, DIMENSION(:,:) :: T, VL, VR
  INTEGER :: N, LDT, LDVL, LDVR, MM, M, INFO
  LOGICAL, DIMENSION(:) :: SELECT
  REAL, DIMENSION(:) :: RWORK
 
  SUBROUTINE TREVC_64( SIDE, HOWMNY, SELECT, [N], T, [LDT], VL, [LDVL], 
 *       VR, [LDVR], MM, M, [WORK], [RWORK], [INFO])
  CHARACTER(LEN=1) :: SIDE, HOWMNY
  COMPLEX, DIMENSION(:) :: WORK
  COMPLEX, DIMENSION(:,:) :: T, VL, VR
  INTEGER(8) :: N, LDT, LDVL, LDVR, MM, M, INFO
  LOGICAL(8), DIMENSION(:) :: SELECT
  REAL, DIMENSION(:) :: RWORK
 

C INTERFACE

void ctrevc(char side, char howmny, logical *select, int n, complex *t, int ldt, complex *vl, int ldvl, complex *vr, int ldvr, int mm, int *m, int *info);

void ctrevc_64(char side, char howmny, logical *select, long n, complex *t, long ldt, complex *vl, long ldvl, complex *vr, long ldvr, long mm, long *m, long *info);

PURPOSE

The right eigenvector x and the left eigenvector y of T corresponding to an eigenvalue w are defined by:

             T*x = w*x,     y'*T = w*y'

where y' denotes the conjugate transpose of the vector y.

If all eigenvectors are requested, the routine may either return the matrices X and/or Y of right or left eigenvectors of T, or the products Q*X and/or Q*Y, where Q is an input unitary

matrix. If T was obtained from the Schur factorization of an original matrix A = Q*T*Q', then Q*X and Q*Y are the matrices of right or left eigenvectors of A.

ARGUMENTS

* SIDE (input)

* HOWMNY (input)

* SELECT (input/output)

If HOWMNY = 'S', SELECT specifies the eigenvectors to be computed. If HOWMNY = 'A' or 'B', SELECT is not referenced. To select the eigenvector corresponding to the j-th eigenvalue, SELECT(j) must be set to .TRUE..

* N (input)

The order of the matrix T. N >= 0.

* T (input/output)

The upper triangular matrix T. T is modified, but restored on exit.

* LDT (input)

The leading dimension of the array T. LDT >= max(1,N).

* VL (input/output)

On entry, if SIDE = 'L' or 'B' and HOWMNY = 'B', VL must contain an N-by-N matrix Q (usually the unitary matrix Q of Schur vectors returned by CHSEQR). On exit, if SIDE = 'L' or 'B', VL contains: if HOWMNY = 'A', the matrix Y of left eigenvectors of T; VL is lower triangular. The i-th column VL(i) of VL is the eigenvector corresponding to T(i,i). if HOWMNY = 'B', the matrix Q*Y; if HOWMNY = 'S', the left eigenvectors of T specified by SELECT, stored consecutively in the columns of VL, in the same order as their eigenvalues. If SIDE = 'R', VL is not referenced.

* LDVL (input)

The leading dimension of the array VL. LDVL >= max(1,N) if SIDE = 'L' or 'B'; LDVL >= 1 otherwise.

* VR (input/output)

On entry, if SIDE = 'R' or 'B' and HOWMNY = 'B', VR must contain an N-by-N matrix Q (usually the unitary matrix Q of Schur vectors returned by CHSEQR). On exit, if SIDE = 'R' or 'B', VR contains: if HOWMNY = 'A', the matrix X of right eigenvectors of T; VR is upper triangular. The i-th column VR(i) of VR is the eigenvector corresponding to T(i,i). if HOWMNY = 'B', the matrix Q*X; if HOWMNY = 'S', the right eigenvectors of T specified by SELECT, stored consecutively in the columns of VR, in the same order as their eigenvalues. If SIDE = 'L', VR is not referenced.

* LDVR (input)

The leading dimension of the array VR. LDVR >= max(1,N) if SIDE = 'R' or 'B'; LDVR >= 1 otherwise.

* MM (input)

The number of columns in the arrays VL and/or VR. MM >= M.

* M (output)

The number of columns in the arrays VL and/or VR actually used to store the eigenvectors. If HOWMNY = 'A' or 'B', M is set to N. Each selected eigenvector occupies one column.

* WORK (workspace)

dimension(2*N)

* RWORK (workspace)

dimension(N)

* INFO (output)