*DECK CG SUBROUTINE CG (NM, N, AR, AI, WR, WI, MATZ, ZR, ZI, FV1, FV2, FV3, + IERR) C***BEGIN PROLOGUE CG C***PURPOSE Compute the eigenvalues and, optionally, the eigenvectors C of a complex general matrix. C***LIBRARY SLATEC (EISPACK) C***CATEGORY D4A4 C***TYPE COMPLEX (RG-S, CG-C) C***KEYWORDS EIGENVALUES, EIGENVECTORS, EISPACK C***AUTHOR Smith, B. T., et al. C***DESCRIPTION C C This subroutine calls the recommended sequence of C subroutines from the eigensystem subroutine package (EISPACK) C to find the eigenvalues and eigenvectors (if desired) C of a COMPLEX GENERAL matrix. C C On INPUT C C NM must be set to the row dimension of the two-dimensional C array parameters, AR, AI, ZR and ZI, as declared in the C calling program dimension statement. NM is an INTEGER C variable. C C N is the order of the matrix A=(AR,AI). N is an INTEGER C variable. N must be less than or equal to NM. C C AR and AI contain the real and imaginary parts, respectively, C of the complex general matrix. AR and AI are two-dimensional C REAL arrays, dimensioned AR(NM,N) and AI(NM,N). C C MATZ is an INTEGER variable set equal to zero if only C eigenvalues are desired. Otherwise, it is set to any C non-zero integer for both eigenvalues and eigenvectors. C C On OUTPUT C C WR and WI contain the real and imaginary parts, respectively, C of the eigenvalues. WR and WI are one-dimensional REAL C arrays, dimensioned WR(N) and WI(N). C C ZR and ZI contain the real and imaginary parts, respectively, C of the eigenvectors if MATZ is not zero. ZR and ZI are C two-dimensional REAL arrays, dimensioned ZR(NM,N) and C ZI(NM,N). C C IERR is an INTEGER flag set to C Zero for normal return, C 10*N if N is greater than NM, C J if the J-th eigenvalue has not been C determined after a total of 30 iterations. C The eigenvalues should be correct for indices C IERR+1, IERR+2, ..., N, but no eigenvectors are C computed. C C FV1, FV2, and FV3 are one-dimensional REAL arrays used for C temporary storage, dimensioned FV1(N), FV2(N), and FV3(N). C C Questions and comments should be directed to B. S. Garbow, C APPLIED MATHEMATICS DIVISION, ARGONNE NATIONAL LABORATORY C ------------------------------------------------------------------ C C***REFERENCES B. T. Smith, J. M. Boyle, J. J. Dongarra, B. S. Garbow, C Y. Ikebe, V. C. Klema and C. B. Moler, Matrix Eigen- C system Routines - EISPACK Guide, Springer-Verlag, C 1976. C***ROUTINES CALLED CBABK2, CBAL, COMQR, COMQR2, CORTH C***REVISION HISTORY (YYMMDD) C 760101 DATE WRITTEN C 890831 Modified array declarations. (WRB) C 890831 REVISION DATE from Version 3.2 C 891214 Prologue converted to Version 4.0 format. (BAB) C 920501 Reformatted the REFERENCES section. (WRB) C***END PROLOGUE CG C INTEGER N,NM,IS1,IS2,IERR,MATZ REAL AR(NM,*),AI(NM,*),WR(*),WI(*),ZR(NM,*),ZI(NM,*) REAL FV1(*),FV2(*),FV3(*) C C***FIRST EXECUTABLE STATEMENT CG IF (N .LE. NM) GO TO 10 IERR = 10 * N GO TO 50 C 10 CALL CBAL(NM,N,AR,AI,IS1,IS2,FV1) CALL CORTH(NM,N,IS1,IS2,AR,AI,FV2,FV3) IF (MATZ .NE. 0) GO TO 20 C .......... FIND EIGENVALUES ONLY .......... CALL COMQR(NM,N,IS1,IS2,AR,AI,WR,WI,IERR) GO TO 50 C .......... FIND BOTH EIGENVALUES AND EIGENVECTORS .......... 20 CALL COMQR2(NM,N,IS1,IS2,FV2,FV3,AR,AI,WR,WI,ZR,ZI,IERR) IF (IERR .NE. 0) GO TO 50 CALL CBABK2(NM,N,IS1,IS2,FV1,N,ZR,ZI) 50 RETURN END