Program f07bafe ! F07BAF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: dgbsv, 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, n ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: ab(:,:), b(:) Integer, Allocatable :: ipiv(:) ! .. Intrinsic Procedures .. Intrinsic :: max, min ! .. Executable Statements .. Write (nout,*) 'F07BAF Example Program Results' Write (nout,*) ! Skip heading in data file Read (nin,*) Read (nin,*) n, kl, ku ldab = 2*kl + ku + 1 Allocate (ab(ldab,n),b(n),ipiv(n)) ! Read the band matrix A and the right hand side 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(1:n) ! Solve the equations Ax = b for x ! The NAG name equivalent of dgbsv is f07baf Call dgbsv(n,kl,ku,1,ab,ldab,ipiv,b,n,info) If (info==0) Then ! Print solution Write (nout,*) 'Solution' Write (nout,99999) b(1:n) ! Print details of the 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(n,n,kl,kl+ku,ab,ldab,'Details of factorization',ifail) ! Print pivot indices' Write (nout,*) Write (nout,*) 'Pivot indices' Write (nout,99998) ipiv(1:n) Else Write (nout,99997) 'The (', info, ',', info, ')', & ' element of the factor U is zero' End If 99999 Format ((3X,7F11.4)) 99998 Format ((3X,7I11)) 99997 Format (1X,A,I3,A,I3,A,A) End Program f07bafe