PROGRAM f08npfe ! F08NPF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. Use Statements .. USE nag_library, ONLY : nag_wp, x02ajf, zgeevx ! .. Implicit None Statement .. IMPLICIT NONE ! .. Parameters .. INTEGER, PARAMETER :: nb = 64, nin = 5, nout = 6 ! .. Local Scalars .. REAL (KIND=nag_wp) :: abnrm, eps, erbnd, rcnd, tol INTEGER :: i, ihi, ilo, info, j, lda, ldvl, & ldvr, lwork, n ! .. Local Arrays .. COMPLEX (KIND=nag_wp), ALLOCATABLE :: a(:,:), vl(:,:), vr(:,:), w(:), & work(:) COMPLEX (KIND=nag_wp) :: dummy(1) REAL (KIND=nag_wp), ALLOCATABLE :: rconde(:), rcondv(:), rwork(:), & scale(:) ! .. Intrinsic Functions .. INTRINSIC max, nint, real ! .. Executable Statements .. WRITE (nout,*) 'F08NPF Example Program Results' ! Skip heading in data file READ (nin,*) READ (nin,*) n lda = n ldvl = n ldvr = n ALLOCATE (a(lda,n),vl(ldvl,n),vr(ldvr,n),w(n),rconde(n),rcondv(n), & rwork(2*n),scale(n)) ! Use routine workspace query to get optimal workspace. lwork = -1 ! The NAG name equivalent of zgeevx is f08npf CALL zgeevx('Balance','Vectors (left)','Vectors (right)', & 'Both reciprocal condition numbers',n,a,lda,w,vl,ldvl,vr,ldvr,ilo, & ihi,scale,abnrm,rconde,rcondv,dummy,lwork,rwork,info) ! Make sure that there is enough workspace for blocksize nb. lwork = max((nb+1)*n,nint(real(dummy(1)))) ALLOCATE (work(lwork)) ! Read the matrix A from data file READ (nin,*) (a(i,1:n),i=1,n) ! Solve the eigenvalue problem ! The NAG name equivalent of zgeevx is f08npf CALL zgeevx('Balance','Vectors (left)','Vectors (right)', & 'Both reciprocal condition numbers',n,a,lda,w,vl,ldvl,vr,ldvr,ilo, & ihi,scale,abnrm,rconde,rcondv,work,lwork,rwork,info) IF (info==0) THEN ! Compute the machine precision eps = x02ajf() tol = eps*abnrm ! Print the eigenvalues and vectors, and associated condition ! number and bounds DO j = 1, n ! Print information on jth eigenvalue WRITE (nout,*) WRITE (nout,99999) 'Eigenvalue(', j, ') = ', w(j) rcnd = rconde(j) WRITE (nout,*) WRITE (nout,99998) 'Reciprocal condition number = ', rcnd IF (rcnd>0.0E0_nag_wp) THEN erbnd = tol/rcnd WRITE (nout,99998) 'Error bound = ', erbnd ELSE WRITE (nout,*) 'Error bound is infinite' END IF ! Print information on jth eigenvector WRITE (nout,*) WRITE (nout,99997) 'Eigenvector(', j, ')', vr(1:n,j) rcnd = rcondv(j) WRITE (nout,*) WRITE (nout,99998) 'Reciprocal condition number = ', rcnd IF (rcnd>0.0E0_nag_wp) THEN erbnd = tol/rcnd WRITE (nout,99998) 'Error bound = ', erbnd ELSE WRITE (nout,*) 'Error bound is infinite' END IF END DO ELSE WRITE (nout,*) WRITE (nout,99996) 'Failure in ZGEEVX. INFO =', info END IF 99999 FORMAT (1X,A,I2,A,'(',1P,E11.4,',',1P,E11.4,')') 99998 FORMAT (1X,A,1P,E8.1) 99997 FORMAT (1X,A,I2,A/3(1X,'(',1P,E11.4,',',1P,E11.4,')':)) 99996 FORMAT (1X,A,I4) END PROGRAM f08npfe