Program f08pnfe ! F08PNF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: f08pnz, nag_wp, x02ajf, x04dbf, zgees, zgemm, & zlange => f06uaf ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nb = 64, nin = 5, nout = 6 ! .. Local Scalars .. Complex (Kind=nag_wp) :: alpha, beta Real (Kind=nag_wp) :: norm Integer :: i, ifail, info, lda, ldc, ldd, ldvs, & lwork, n, sdim ! .. Local Arrays .. Complex (Kind=nag_wp), Allocatable :: a(:,:), c(:,:), d(:,:), vs(:,:), & w(:), work(:) Complex (Kind=nag_wp) :: wdum(1) Real (Kind=nag_wp), Allocatable :: rwork(:) Logical :: dummy(1) Character (1) :: clabs(1), rlabs(1) ! .. Intrinsic Procedures .. Intrinsic :: cmplx, max, nint, real ! .. Executable Statements .. Write (nout,*) 'F08PNF Example Program Results' Write (nout,*) Flush (nout) ! Skip heading in data file Read (nin,*) Read (nin,*) n lda = n ldc = n ldd = n ldvs = n Allocate (a(lda,n),vs(ldvs,n),c(ldc,n),d(ldd,n),w(n),rwork(n)) ! Use routine workspace query to get optimal workspace. lwork = -1 ! The NAG name equivalent of zgees is f08pnf Call zgees('Vectors (Schur)','No sort',f08pnz,n,a,lda,sdim,w,vs,ldvs, & wdum,lwork,rwork,dummy,info) ! Make sure that there is enough workspace for blocksize nb. lwork = max((nb+1)*n,nint(real(wdum(1)))) Allocate (work(lwork)) ! Read the matrix A from data file Read (nin,*)(a(i,1:n),i=1,n) ! Copy A into D d(1:ldd,1:n) = a(1:lda,1:n) ! print matrix A ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 Call x04dbf('General',' ',n,n,a,lda,'Bracketed','F7.4','Matrix A', & 'Integer',rlabs,'Integer',clabs,80,0,ifail) Write (nout,*) Flush (nout) ! Find the Schur factorization ! The NAG name equivalent of zgees is f08pnf Call zgees('Vectors (Schur)','No sort',f08pnz,n,a,lda,sdim,w,vs,ldvs, & work,lwork,rwork,dummy,info) If (info>0) Then Write (nout,99999) 'Failure in ZGEES. INFO =', info Else ! Compute A - Z*T*Z^H from Schur factorization of A and store in matrix D ! The NAG name equivelent of zgemm is f06zaf alpha = cmplx(1,kind=nag_wp) beta = cmplx(0,kind=nag_wp) Call zgemm('N','N',n,n,n,alpha,vs,ldvs,a,lda,beta,c,ldc) alpha = cmplx(-1,kind=nag_wp) beta = cmplx(1,kind=nag_wp) Call zgemm('N','C',n,n,n,alpha,c,ldc,vs,ldvs,beta,d,ldd) ! Find norm of matrix D and print warning if it is too large ! f06uaf is the NAG name equivalent of the LAPACK auxiliary zlange norm = zlange('O',ldd,n,d,ldd,rwork) If (norm>x02ajf()**0.8_nag_wp) Then Write (nout,*) 'Norm of A-(Z*T*Z^H) is much greater than 0.' Write (nout,*) 'Schur factorization has failed.' Else ! Print eigenvalues. Write (nout,*) 'Eigenvalues' Write (nout,99998)(w(i),i=1,n) End If End If 99999 Format (1X,A,I4) 99998 Format ((3X,4(' (',F7.4,',',F7.4,')':))) End Program f08pnfe