Program f08lefe ! F08LEF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: dgbbrd, nag_wp ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 Character (1), Parameter :: vect = 'B' ! .. Local Scalars .. Integer :: i, info, j, kl, ku, ldab, ldb, ldc, & ldpt, ldq, m, n, ncc ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: ab(:,:), b(:,:), c(:,:), d(:), e(:), & pt(:,:), q(:,:), work(:) ! .. Intrinsic Procedures .. Intrinsic :: abs, max, min ! .. Executable Statements .. Continue Write (nout,*) 'F08LEF Example Program Results' ! Skip heading in data file Read (nin,*) Read (nin,*) m, n, kl, ku, ncc ldab = kl + ku + 1 ldb = m ldc = m ldpt = n ldq = m Allocate (ab(ldab,n),b(ldb,n),c(m,ncc),d(n),e(n-1),pt(ldpt,n),q(ldq,m), & work(2*m+2*n)) ! Read A from data file Read (nin,*)((ab(ku+1+i-j,j),j=max(i-kl,1),min(i+ku,n)),i=1,m) ! Reduce A to upper bidiagonal form ! The NAG name equivalent of dgbbrd is f08lef Call dgbbrd(vect,m,n,ncc,kl,ku,ab,ldab,d,e,q,ldq,pt,ldpt,c,ldc,work, & info) ! Print the absolute values of bidiagonal vectors d and e. ! Any of these can differ by a sign change by combinations of sign ! changes in columns of Q and P (rows of PT). Write (nout,*) Write (nout,*) 'Diagonal D:' Write (nout,99999) abs(d(1:n)) Write (nout,*) Write (nout,*) 'Off-diagonal E:' Write (nout,99999) abs(e(1:n-1)) 99999 Format (1X,4(3X,F11.4)) End Program f08lefe