dgeev.f3

!>
!> DGEEV computes for an N-by-N real nonsymmetric matrix A, the
!> eigenvalues and, optionally, the left and/or right eigenvectors.
!>
!> The right eigenvector v(j) of A satisfies
!>                  A * v(j) = lambda(j) * v(j)
!> where lambda(j) is its eigenvalue.
!> The left eigenvector u(j) of A satisfies
!>               u(j)**H * A = lambda(j) * u(j)**H
!> where u(j)**H denotes the conjugate-transpose of u(j).
!>
!> The computed eigenvectors are normalized to have Euclidean norm
!> equal to 1 and largest component real.
!> 

JOBVL

!>          JOBVL is CHARACTER*1
!>          = 'N': left eigenvectors of A are not computed;
!>          = 'V': left eigenvectors of A are computed.
!> 

JOBVR

!>          JOBVR is CHARACTER*1
!>          = 'N': right eigenvectors of A are not computed;
!>          = 'V': right eigenvectors of A are computed.
!> 

N

!>          N is INTEGER
!>          The order of the matrix A. N >= 0.
!> 

A

!>          A is DOUBLE PRECISION array, dimension (LDA,N)
!>          On entry, the N-by-N matrix A.
!>          On exit, A has been overwritten.
!> 

LDA

!>          LDA is INTEGER
!>          The leading dimension of the array A.  LDA >= max(1,N).
!> 

WR

!>          WR is DOUBLE PRECISION array, dimension (N)
!> 

WI

!>          WI is DOUBLE PRECISION array, dimension (N)
!>          WR and WI contain the real and imaginary parts,
!>          respectively, of the computed eigenvalues.  Complex
!>          conjugate pairs of eigenvalues appear consecutively
!>          with the eigenvalue having the positive imaginary part
!>          first.
!> 

VL

!>          VL is DOUBLE PRECISION array, dimension (LDVL,N)
!>          If JOBVL = 'V', the left eigenvectors u(j) are stored one
!>          after another in the columns of VL, in the same order
!>          as their eigenvalues.
!>          If JOBVL = 'N', VL is not referenced.
!>          If the j-th eigenvalue is real, then u(j) = VL(:,j),
!>          the j-th column of VL.
!>          If the j-th and (j+1)-st eigenvalues form a complex
!>          conjugate pair, then u(j) = VL(:,j) + i*VL(:,j+1) and
!>          u(j+1) = VL(:,j) - i*VL(:,j+1).
!> 

LDVL

!>          LDVL is INTEGER
!>          The leading dimension of the array VL.  LDVL >= 1; if
!>          JOBVL = 'V', LDVL >= N.
!> 

VR

!>          VR is DOUBLE PRECISION array, dimension (LDVR,N)
!>          If JOBVR = 'V', the right eigenvectors v(j) are stored one
!>          after another in the columns of VR, in the same order
!>          as their eigenvalues.
!>          If JOBVR = 'N', VR is not referenced.
!>          If the j-th eigenvalue is real, then v(j) = VR(:,j),
!>          the j-th column of VR.
!>          If the j-th and (j+1)-st eigenvalues form a complex
!>          conjugate pair, then v(j) = VR(:,j) + i*VR(:,j+1) and
!>          v(j+1) = VR(:,j) - i*VR(:,j+1).
!> 

LDVR

!>          LDVR is INTEGER
!>          The leading dimension of the array VR.  LDVR >= 1; if
!>          JOBVR = 'V', LDVR >= N.
!> 

WORK

!>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
!>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
!> 

LWORK

!>          LWORK is INTEGER
!>          The dimension of the array WORK.  LWORK >= max(1,3*N), and
!>          if JOBVL = 'V' or JOBVR = 'V', LWORK >= 4*N.  For good
!>          performance, LWORK must generally be larger.
!>
!>          If LWORK = -1, then a workspace query is assumed; the routine
!>          only calculates the optimal size of the WORK array, returns
!>          this value as the first entry of the WORK array, and no error
!>          message related to LWORK is issued by XERBLA.
!> 

INFO

!>          INFO is INTEGER
!>          = 0:  successful exit
!>          < 0:  if INFO = -i, the i-th argument had an illegal value.
!>          > 0:  if INFO = i, the QR algorithm failed to compute all the
!>                eigenvalues, and no eigenvectors have been computed;
!>                elements i+1:N of WR and WI contain eigenvalues which
!>                have converged.
!> 

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