PROGRAM f07befe ! F07BEF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. Use Statements .. USE nag_library, ONLY : dgbtrf, dgbtrs, nag_wp, x04caf ! .. Implicit None Statement .. IMPLICIT NONE ! .. Parameters .. INTEGER, PARAMETER :: nin = 5, nout = 6 CHARACTER (1), PARAMETER :: trans = 'N' ! .. Local Scalars .. INTEGER :: i, ifail, info, j, k, kl, ku, ldab, & ldb, n, nrhs ! .. Local Arrays .. REAL (KIND=nag_wp), ALLOCATABLE :: ab(:,:), b(:,:) INTEGER, ALLOCATABLE :: ipiv(:) ! .. Intrinsic Functions .. INTRINSIC max, min ! .. Executable Statements .. WRITE (nout,*) 'F07BEF Example Program Results' ! Skip heading in data file READ (nin,*) READ (nin,*) n, nrhs, kl, ku ldab = 2*kl + ku + 1 ldb = n ALLOCATE (ab(ldab,n),b(ldb,nrhs),ipiv(n)) ! Read A and B 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,n) READ (nin,*) (b(i,1:nrhs),i=1,n) ! Factorize A ! The NAG name equivalent of dgbtrf is f07bdf CALL dgbtrf(n,n,kl,ku,ab,ldab,ipiv,info) WRITE (nout,*) FLUSH (nout) IF (info==0) THEN ! Compute solution ! The NAG name equivalent of dgbtrs is f07bef CALL dgbtrs(trans,n,kl,ku,nrhs,ab,ldab,ipiv,b,ldb,info) ! Print solution ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 CALL x04caf('General',' ',n,nrhs,b,ldb,'Solution(s)',ifail) ELSE WRITE (nout,*) 'The factor U is singular' END IF END PROGRAM f07befe