PROGRAM f07bdfe ! F07BDF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. Use Statements .. USE nag_library, ONLY : dgbtrf, nag_wp, x04cef ! .. Implicit None Statement .. IMPLICIT NONE ! .. Parameters .. INTEGER, PARAMETER :: nin = 5, nout = 6 ! .. Local Scalars .. INTEGER :: i, ifail, info, j, k, kl, ku, ldab, & m, n ! .. Local Arrays .. REAL (KIND=nag_wp), ALLOCATABLE :: ab(:,:) INTEGER, ALLOCATABLE :: ipiv(:) ! .. Intrinsic Functions .. INTRINSIC max, min ! .. Executable Statements .. WRITE (nout,*) 'F07BDF Example Program Results' ! Skip heading in data file READ (nin,*) READ (nin,*) m, n, kl, ku ldab = 2*kl + ku + 1 ALLOCATE (ab(ldab,n),ipiv(n)) ! Read A from data file k = kl + ku + 1 READ (nin,*) ((ab(k+i-j,j),j=max(i-kl,1),min(i+ku,n)),i=1,m) ! Factorize A ! The NAG name equivalent of dgbtrf is f07bdf CALL dgbtrf(m,n,kl,ku,ab,ldab,ipiv,info) ! Print details of factorization WRITE (nout,*) FLUSH (nout) ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 CALL x04cef(m,n,kl,kl+ku,ab,ldab,'Details of factorization',ifail) ! Print pivot indices WRITE (nout,*) WRITE (nout,*) 'IPIV' WRITE (nout,99999) ipiv(1:min(m,n)) IF (info/=0) WRITE (nout,*) 'The factor U is singular' 99999 FORMAT ((3X,7I11)) END PROGRAM f07bdfe