Program f08qlfe ! F08QLF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: dlange => f06raf, dtrevc, dtrsna, nag_wp, x02ajf ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Real (Kind=nag_wp) :: eps, tnorm Integer :: i, info, ldt, ldvl, ldvr, ldwork, m, n ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: s(:), sep(:), t(:,:), vl(:,:), & vr(:,:), work(:,:) Integer, Allocatable :: iwork(:) Logical :: select(1) ! .. Executable Statements .. Write (nout,*) 'F08QLF Example Program Results' Write (nout,*) ! Skip heading in data file Read (nin,*) Read (nin,*) n ldt = n ldvl = n ldvr = n ldwork = n Allocate (s(n),sep(n),t(ldt,n),vl(ldvl,n),vr(ldvr,n),work(ldwork,n+6), & iwork(2*n-1)) ! Read T from data file Read (nin,*)(t(i,1:n),i=1,n) ! Calculate the left and right eigenvectors of T ! The NAG name equivalent of dtrevc is f08qkf Call dtrevc('Both','All',select,n,t,ldt,vl,ldvl,vr,ldvr,n,m,work,info) ! Estimate condition numbers for all the eigenvalues and right ! eigenvectors of T ! The NAG name equivalent of dtrsna is f08qlf Call dtrsna('Both','All',select,n,t,ldt,vl,ldvl,vr,ldvr,s,sep,n,m,work, & ldwork,iwork,info) ! Print condition numbers of eigenvalues and right eigenvectors Write (nout,*) 'S' Write (nout,99999) s(1:m) Write (nout,*) Write (nout,*) 'SEP' Write (nout,99999) sep(1:m) ! Calculate approximate error estimates (using the 1-norm) eps = x02ajf() ! f06raf is the NAG name equivalent of the LAPACK auxiliary dlange tnorm = dlange('1-norm',n,n,t,ldt,work) Write (nout,*) Write (nout,*) 'Approximate error estimates for eigenvalues ', & 'of T (machine-dependent)' Write (nout,99999)(eps*tnorm/s(i),i=1,m) Write (nout,*) Write (nout,*) 'Approximate error estimates for right ', & 'eigenvectors of T (machine-dependent)' Write (nout,99999)(eps*tnorm/sep(i),i=1,m) 99999 Format ((3X,1P,7E11.1)) End Program f08qlfe