Program f08nefe ! F08NEF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: dgehrd, nag_wp, x04caf ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Real (Kind=nag_wp), Parameter :: zero = 0.0E0_nag_wp Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Integer :: i, ifail, info, lda, lwork, n ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: a(:,:), tau(:), work(:) ! .. Executable Statements .. Write (nout,*) 'F08NEF Example Program Results' ! Skip heading in data file Read (nin,*) Read (nin,*) n lda = n lwork = 64*n Allocate (a(lda,n),tau(n-1),work(lwork)) ! Read A from data file Read (nin,*)(a(i,1:n),i=1,n) ! Reduce A to upper Hessenberg form ! The NAG name equivalent of dgehrd is f08nef Call dgehrd(n,1,n,a,lda,tau,work,lwork,info) ! Set the elements below the first sub-diagonal to zero Do i = 1, n - 2 a(i+2:n,i) = zero End Do ! Print upper Hessenberg form Write (nout,*) Flush (nout) ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 Call x04caf('General',' ',n,n,a,lda,'Upper Hessenberg form',ifail) End Program f08nefe