PROGRAM f11jefe ! F11JEF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. Use Statements .. USE nag_library, ONLY : f11jef, nag_wp ! .. Implicit None Statement .. IMPLICIT NONE ! .. Parameters .. INTEGER, PARAMETER :: nin = 5, nout = 6 ! .. Local Scalars .. REAL (KIND=nag_wp) :: omega, rnorm, tol INTEGER :: i, ifail, itn, lwork, maxitn, n, nnz CHARACTER (6) :: method CHARACTER (1) :: precon ! .. Local Arrays .. REAL (KIND=nag_wp), ALLOCATABLE :: a(:), b(:), work(:), x(:) INTEGER, ALLOCATABLE :: icol(:), irow(:), iwork(:) ! .. Executable Statements .. WRITE (nout,*) 'F11JEF Example Program Results' ! Skip heading in data file READ (nin,*) ! Read algorithmic parameters READ (nin,*) n READ (nin,*) nnz lwork = 7*n + 120 ALLOCATE (a(nnz),b(n),work(lwork),x(n),icol(nnz),irow(nnz),iwork(n+1)) READ (nin,*) method, precon READ (nin,*) omega READ (nin,*) tol, maxitn ! Read 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 x READ (nin,*) b(1:n) READ (nin,*) x(1:n) ! Solve Ax = b using F11JEF ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 CALL f11jef(method,precon,n,nnz,a,irow,icol,omega,b,tol,maxitn,x,rnorm, & itn,work,lwork,iwork,ifail) WRITE (nout,99999) 'Converged in', itn, ' iterations' WRITE (nout,99998) 'Final residual norm =', rnorm ! Output x WRITE (nout,99997) x(1:n) 99999 FORMAT (1X,A,I10,A) 99998 FORMAT (1X,A,1P,E16.3) 99997 FORMAT (1X,1P,E16.4) END PROGRAM f11jefe