Program f08fqfe ! F08FQF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: blas_zamax_val, nag_wp, x04daf, zheevd ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Real (Kind=nag_wp) :: r Integer :: i, ifail, info, k, lda, liwork, & lrwork, lwork, n Character (1) :: job, uplo ! .. Local Arrays .. Complex (Kind=nag_wp), Allocatable :: a(:,:), work(:) Real (Kind=nag_wp), Allocatable :: rwork(:), w(:) Integer, Allocatable :: iwork(:) ! .. Intrinsic Procedures .. Intrinsic :: abs, cmplx, conjg ! .. Executable Statements .. Write (nout,*) 'F08FQF Example Program Results' ! Skip heading in data file Read (nin,*) Read (nin,*) n lda = n liwork = 5*n + 3 lrwork = 2*n*n + 5*n + 1 lwork = n*(n+2) Allocate (a(lda,n),work(lwork),rwork(lrwork),w(n),iwork(liwork)) Read (nin,*) uplo ! Read A from data file If (uplo=='U') Then Read (nin,*)(a(i,i:n),i=1,n) Else If (uplo=='L') Then Read (nin,*)(a(i,1:i),i=1,n) End If Read (nin,*) job ! Calculate all the eigenvalues and eigenvectors of A ! The NAG name equivalent of zheevd is f08fqf Call zheevd(job,uplo,n,a,lda,w,work,lwork,rwork,lrwork,iwork,liwork, & info) Write (nout,*) If (info>0) Then Write (nout,*) 'Failure to converge.' Else ! Print eigenvalues and eigenvectors Write (nout,*) 'Eigenvalues' Do i = 1, n Write (nout,99999) i, w(i) End Do Write (nout,*) Flush (nout) ! Normalize the eigenvectors so that the element of largest absolute ! value is real. Do i = 1, n Call blas_zamax_val(n,a(1,i),1,k,r) a(1:n,i) = a(1:n,i)*(conjg(a(k,i))/cmplx(abs(a(k,i)),kind=nag_wp)) End Do ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 Call x04daf('General',' ',n,n,a,lda,'Eigenvectors',ifail) End If 99999 Format (3X,I5,5X,2F8.4) End Program f08fqfe