I am trying to get the ZGEEV routine in Lapack to work for a test problem and having some difficulties. I just started coding in FORTRAN a week ago, so I think it is probably something very trivial that I am missing.
I have to diagonalize rather large complex symmetric matrices. To get started, using Matlab I created a 200 by 200 matrix, which I have verified is diagonalizable. When I run the code, it brings up no errors and the INFO = 0, suggesting a success. However, all the eigenvalues are (0,0) which I know is wrong.
Attached is my code.
PROGRAM speed_zgeev
IMPLICIT NONE
INTEGER(8) :: N
COMPLEX*16, DIMENSION(:,:), ALLOCATABLE :: MAT
INTEGER(8) :: INFO, I, J
COMPLEX*16, DIMENSION(:), ALLOCATABLE :: RWORK
COMPLEX*16, DIMENSION(:), ALLOCATABLE :: D
COMPLEX*16, DIMENSION(1,1) :: VR, VL
INTEGER(8) :: LWORK = -1
COMPLEX*16, DIMENSION(:), ALLOCATABLE :: WORK
DOUBLE PRECISION :: RPART, IPART
EXTERNAL ZGEEV
N = 200
ALLOCATE(D(N))
ALLOCATE(RWORK(2*N))
ALLOCATE(WORK(N))
ALLOCATE(MAT(N,N))
OPEN(UNIT = 31, FILE = "newmat.txt")
OPEN(UNIT = 32, FILE = "newmati.txt")
DO J = 1,N
DO I = 1,N
READ(31,*) RPART
READ(32,*) IPART
MAT(I,J) = CMPLX(RPART, IPART)
END DO
END DO
CLOSE(31)
CLOSE(32)
CALL ZGEEV('N','N', N, MAT, N, D, VL, 1, VR, 1, WORK, LWORK, RWORK, INFO)
INFO = WORK(1)
DEALLOCATE(WORK)
ALLOCATE(WORK(INFO))
CALL ZGEEV('N','N', N, MAT, N, D, VL, 1, VR, 1, WORK, LWORK, RWORK, INFO)
IF (INFO .EQ. 0) THEN
PRINT*, D(1:10)
ELSE
PRINT*, INFO
END IF
DEALLOCATE(MAT)
DEALLOCATE(D)
DEALLOCATE(RWORK)
DEALLOCATE(WORK)
END PROGRAM speed_zgeev
I have tried the same code on smaller matrices, of size 30 by 30 and they work fine. Any help would be appreciated! Thanks.
I forgot to mention that I am loading the matrices from a test file which I have verified to be working right.
