Program f08uqfe ! F08UQF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: nag_wp, zhbgvd ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 Character (1), Parameter :: uplo = 'U' ! .. Local Scalars .. Integer :: i, info, j, ka, kb, ldab, ldbb, & liwork, lrwork, lwork, n ! .. Local Arrays .. Complex (Kind=nag_wp), Allocatable :: ab(:,:), bb(:,:), work(:) Complex (Kind=nag_wp) :: dummy(1,1) Real (Kind=nag_wp), Allocatable :: rwork(:), w(:) Integer, Allocatable :: iwork(:) ! .. Intrinsic Procedures .. Intrinsic :: max, min ! .. Executable Statements .. Write (nout,*) 'F08UQF Example Program Results' Write (nout,*) ! Skip heading in data file Read (nin,*) Read (nin,*) n, ka, kb ldab = ka + 1 ldbb = kb + 1 lrwork = n lwork = n liwork = 1 Allocate (ab(ldab,n),bb(ldbb,n),work(lwork),rwork(lrwork),w(n), & iwork(liwork)) ! Read the upper or lower triangular parts of the matrices A and ! B from data file If (uplo=='U') Then Read (nin,*)((ab(ka+1+i-j,j),j=i,min(n,i+ka)),i=1,n) Read (nin,*)((bb(kb+1+i-j,j),j=i,min(n,i+kb)),i=1,n) Else If (uplo=='L') Then Read (nin,*)((ab(1+i-j,j),j=max(1,i-ka),i),i=1,n) Read (nin,*)((bb(1+i-j,j),j=max(1,i-kb),i),i=1,n) End If ! Solve the generalized Hermitian band eigenvalue problem ! A*x = lambda*B*x ! The NAG name equivalent of zhbgvd is f08uqf Call zhbgvd('No vectors',uplo,n,ka,kb,ab,ldab,bb,ldbb,w,dummy,1,work, & lwork,rwork,lrwork,iwork,liwork,info) If (info==0) Then ! Print solution Write (nout,*) 'Eigenvalues' Write (nout,99999) w(1:n) Else If (info>n .And. info<=2*n) Then i = info - n Write (nout,99998) 'The leading minor of order ', i, & ' of B is not positive definite' Else Write (nout,99997) 'Failure in ZHBGVD. INFO =', info End If 99999 Format (3X,(6F11.4)) 99998 Format (1X,A,I4,A) 99997 Format (1X,A,I4) End Program f08uqfe