PROGRAM f11dsfe ! F11DSF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. Use Statements .. USE nag_library, ONLY : f11dsf, 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, l, lwork, m, maxitn, & n, nnz CHARACTER (8) :: method CHARACTER (1) :: precon ! .. Local Arrays .. COMPLEX (KIND=nag_wp), ALLOCATABLE :: a(:), b(:), work(:), x(:) INTEGER, ALLOCATABLE :: icol(:), irow(:), iwork(:) ! .. Intrinsic Functions .. INTRINSIC max ! .. Executable Statements .. WRITE (nout,*) 'F11DSF Example Program Results' WRITE (nout,*) ! Skip heading in data file READ (nin,*) ! Read algorithmic parameters READ (nin,*) n READ (nin,*) nnz READ (nin,*) method, precon READ (nin,*) omega READ (nin,*) m, tol, maxitn l = n IF (precon=='N' .OR. precon=='n') l = 0 lwork = max(4*n+m*(m+n+5)+l+121,8*n+l+120,2*n*(m+3)+m*(m+2)+l+120, & 11*n+l+120) ALLOCATE (a(nnz),b(n),work(lwork),x(n),icol(nnz),irow(nnz), & iwork(2*n+1)) ! Read the matrix A DO i = 1, nnz READ (nin,*) a(i), irow(i), icol(i) END DO ! Read rhs vector b and initial approximate solution x READ (nin,*) b(1:n) READ (nin,*) x(1:n) ! Solve Ax = b using F11DSF ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 CALL f11dsf(method,precon,n,nnz,a,irow,icol,omega,b,m,tol,maxitn,x, & rnorm,itn,work,lwork,iwork,ifail) WRITE (nout,99999) itn WRITE (nout,99998) rnorm WRITE (nout,*) ! Output x WRITE (nout,*) ' X' WRITE (nout,99997) x(1:n) 99999 FORMAT (1X,'Converged in',I10,' iterations') 99998 FORMAT (1X,'Final residual norm =',1P,E16.3) 99997 FORMAT (1X,'(',1P,E16.4,',',1P,E16.4,')') END PROGRAM f11dsfe