Program f08wnfe ! F08WNF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: nag_wp, x02amf, zggev ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nb = 64, nin = 5, nout = 6 ! .. Local Scalars .. Real (Kind=nag_wp) :: small Integer :: i, info, j, lda, ldb, ldvr, lwork, n ! .. Local Arrays .. Complex (Kind=nag_wp), Allocatable :: a(:,:), alpha(:), b(:,:), beta(:), & vr(:,:), work(:) Complex (Kind=nag_wp) :: dummy(1,1) Real (Kind=nag_wp), Allocatable :: rwork(:) ! .. Intrinsic Procedures .. Intrinsic :: abs, max, nint, real ! .. Executable Statements .. Write (nout,*) 'F08WNF Example Program Results' ! Skip heading in data file Read (nin,*) Read (nin,*) n lda = n ldb = n ldvr = n Allocate (a(lda,n),alpha(n),b(ldb,n),beta(n),vr(ldvr,n),rwork(8*n)) ! Use routine workspace query to get optimal workspace. lwork = -1 ! The NAG name equivalent of zggev is f08wnf Call zggev('No left vectors','Vectors (right)',n,a,lda,b,ldb,alpha,beta, & dummy,1,vr,ldvr,dummy,lwork,rwork,info) ! Make sure that there is enough workspace for blocksize nb. lwork = max((nb+1)*n,nint(real(dummy(1,1)))) Allocate (work(lwork)) ! Read in the matrices A and B Read (nin,*)(a(i,1:n),i=1,n) Read (nin,*)(b(i,1:n),i=1,n) ! Solve the generalized eigenvalue problem ! The NAG name equivalent of zggev is f08wnf Call zggev('No left vectors','Vectors (right)',n,a,lda,b,ldb,alpha,beta, & dummy,1,vr,ldvr,work,lwork,rwork,info) ! Normalize the eigenvectors Do i = 1, n vr(1:n,i) = vr(1:n,i)/vr(1,i) End Do If (info>0) Then Write (nout,*) Write (nout,99999) 'Failure in ZGGEV. INFO =', info Else small = x02amf() Do j = 1, n Write (nout,*) If ((abs(alpha(j)))*small>=abs(beta(j))) Then Write (nout,99998) 'Eigenvalue(', j, ')', & ' is numerically infinite or undetermined', 'ALPHA(', j, ') = ', & alpha(j), ', BETA(', j, ') = ', beta(j) Else Write (nout,99997) 'Eigenvalue(', j, ') = ', alpha(j)/beta(j) End If Write (nout,*) Write (nout,99996) 'Eigenvector(', j, ')', (vr(i,j),i=1,n) End Do End If 99999 Format (1X,A,I4) 99998 Format (1X,A,I2,2A/1X,2(A,I2,A,'(',1P,E11.4,',',1P,E11.4,')')) 99997 Format (1X,A,I2,A,'(',1P,E11.4,',',1P,E11.4,')') 99996 Format (1X,A,I2,A/3(1X,'(',1P,E11.4,',',1P,E11.4,')':)) End Program f08wnfe