Program f08qyfe ! F08QYF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: f06uaf, nag_wp, x02ajf, ztrevc, ztrsna ! .. 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 .. Complex (Kind=nag_wp), Allocatable :: t(:,:), vl(:,:), vr(:,:), work(:,:) Real (Kind=nag_wp), Allocatable :: rwork(:), s(:), sep(:) Logical :: select(1) ! .. Executable Statements .. Write (nout,*) 'F08QYF Example Program Results' Write (nout,*) ! Skip heading in data file Read (nin,*) Read (nin,*) n ldt = n ldvl = n ldvr = n ldwork = n Allocate (t(ldt,n),vl(ldvl,n),vr(ldvr,n),work(ldwork,n+1),rwork(n),s(n), & sep(n)) ! 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 ztrevc is f08qxf Call ztrevc('Both','All',select,n,t,ldt,vl,ldvl,vr,ldvr,n,m,work,rwork, & info) ! Estimate condition numbers for all the eigenvalues and right ! eigenvectors of T ! The NAG name equivalent of ztrsna is f08qyf Call ztrsna('Both','All',select,n,t,ldt,vl,ldvl,vr,ldvr,s,sep,n,m,work, & ldwork,rwork,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() tnorm = f06uaf('1-norm',n,n,t,ldt,rwork) 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 f08qyfe