Program f04bbfe ! F04BBF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: f04bbf, nag_wp, x04caf, x04cef ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Real (Kind=nag_wp) :: errbnd, rcond Integer :: i, ierr, ifail, j, k, kl, ku, ldab, & ldb, n, nrhs ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: ab(:,:), b(:,:) Integer, Allocatable :: ipiv(:) ! .. Intrinsic Procedures .. Intrinsic :: max, min ! .. Executable Statements .. Write (nout,*) 'F04BBF Example Program Results' Write (nout,*) Flush (nout) ! Skip heading in data file Read (nin,*) Read (nin,*) n, kl, ku, nrhs 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) ! Solve the equations AX = B for X ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 1 Call f04bbf(n,kl,ku,nrhs,ab,ldab,ipiv,b,ldb,rcond,errbnd,ifail) If (ifail==0) Then ! Print solution, estimate of condition number and approximate ! error bound ierr = 0 Call x04caf('General',' ',n,nrhs,b,ldb,'Solution',ierr) Write (nout,*) Write (nout,*) 'Estimate of condition number' Write (nout,99999) 1.0E0_nag_wp/rcond Write (nout,*) Write (nout,*) 'Estimate of error bound for computed solutions' Write (nout,99999) errbnd Else If (ifail==n+1) Then ! Matrix A is numerically singular. Print estimate of ! reciprocal of condition number and solution Write (nout,*) Write (nout,*) 'Estimate of reciprocal of condition number' Write (nout,99999) rcond Write (nout,*) Flush (nout) ierr = 0 Call x04caf('General',' ',n,nrhs,b,ldb,'Solution',ierr) Else If (ifail>0 .And. ifail<=n) Then ! The upper triangular matrix U is exactly singular. Print ! details of factorization Write (nout,*) Flush (nout) ierr = 0 Call x04cef(n,n,kl,kl+ku,ab,ldab,'Details of factorization',ierr) ! Print pivot indices Write (nout,*) Write (nout,*) 'Pivot indices' Write (nout,99998) ipiv(1:n) Else Write (nout,99997) ifail End If 99999 Format (6X,1P,E9.1) 99998 Format ((1X,7I11)) 99997 Format (1X,' ** F04BBF returned with IFAIL = ',I5) End Program f04bbfe