Program f11dkfe ! F11DKF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: f11bdf, f11bef, f11bff, f11dkf, f11xaf, nag_wp ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Real (Kind=nag_wp) :: anorm, sigmax, stplhs, stprhs, tol Integer :: i, ifail, ifail1, irevcm, iterm, & itn, lwork, lwreq, m, maxitn, monit, & n, niter, nnz Character (1) :: init, norm, precon, weight Character (8) :: method ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: a(:), b(:), diag(:), wgt(:), & work(:), x(:) Integer, Allocatable :: icol(:), irow(:) ! .. Executable Statements .. Write (nout,*) 'F11DKF Example Program Results' ! Skip heading in data file Read (nin,*) Read (nin,*) n Read (nin,*) nnz lwork = 200 Allocate (a(nnz),b(n),diag(n),wgt(n),work(lwork),x(n),icol(nnz), & irow(nnz)) ! Read or initialize the parameters for the iterative solver Read (nin,*) method Read (nin,*) precon, norm, weight, iterm Read (nin,*) m, tol, maxitn Read (nin,*) monit anorm = 0.0E0_nag_wp sigmax = 0.0E0_nag_wp ! Read the parameters for the preconditioner Read (nin,*) niter ! Read the non-zero elements of the matrix A Do i = 1, nnz Read (nin,*) a(i), irow(i), icol(i) End Do ! Read right-hand side vector b and initial approximate solution Read (nin,*) b(1:n) Read (nin,*) x(1:n) ! Call F11BDF to initialize the solver ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 Call f11bdf(method,precon,norm,weight,iterm,n,m,tol,maxitn,anorm,sigmax, & monit,lwreq,work,lwork,ifail) ! Call repeatedly F11BEF to solve the equations ! Note that the arrays B and X are overwritten ! On final exit, X will contain the solution and B the residual ! vector irevcm = 0 init = 'I' ifail = 1 loop: Do Call f11bef(irevcm,x,b,wgt,work,lwreq,ifail) If (irevcm/=4) Then ifail1 = -1 Select Case (irevcm) Case (-1) Call f11xaf('Transpose',n,nnz,a,irow,icol,'No checking',x,b, & ifail1) Case (1) Call f11xaf('No transpose',n,nnz,a,irow,icol,'No checking',x,b, & ifail1) Case (2) Call f11dkf('Non symmetric','N',init,niter,n,nnz,a,irow,icol, & 'Check',x,b,diag,work(lwreq+1),ifail1) init = 'N' Case (3) ifail1 = 0 Call f11bff(itn,stplhs,stprhs,anorm,sigmax,work,lwreq,ifail1) Write (nout,99999) itn, stplhs End Select If (ifail1/=0) irevcm = 6 Else If (ifail/=0) Then Write (nout,99993) ifail Go To 100 Else Exit loop End If End Do loop ! Obtain information about the computation ifail1 = 0 Call f11bff(itn,stplhs,stprhs,anorm,sigmax,work,lwreq,ifail1) ! Print the output data Write (nout,99996) Write (nout,99995) 'Number of iterations for convergence: ', itn Write (nout,99994) 'Residual norm: ', stplhs Write (nout,99994) 'Right-hand side of termination criterion:', stprhs Write (nout,99994) '1-norm of matrix A: ', anorm ! Output x Write (nout,99998) Write (nout,99997)(x(i),b(i),i=1,n) 100 Continue 99999 Format (/1X,'Monitoring at iteration no.',I4/1X,1P,'residual no','rm: ', & E14.4) 99998 Format (/2X,' Solution vector',2X,' Residual vector') 99997 Format (1X,1P,E16.4,1X,E16.4) 99996 Format (/1X,'Final Results') 99995 Format (1X,A,I4) 99994 Format (1X,A,1P,E14.4) 99993 Format (1X/1X,' ** F11BEF returned with IFAIL = ',I5) End Program f11dkfe