PROGRAM f04ccfe ! F04CCF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. Use Statements .. USE nag_library, ONLY : f04ccf, nag_wp, x04dbf ! .. Implicit None Statement .. IMPLICIT NONE ! .. Parameters .. INTEGER, PARAMETER :: nin = 5, nout = 6 ! .. Local Scalars .. REAL (KIND=nag_wp) :: errbnd, rcond INTEGER :: i, ierr, ifail, ldb, n, nrhs ! .. Local Arrays .. COMPLEX (KIND=nag_wp), ALLOCATABLE :: b(:,:), d(:), dl(:), du(:), du2(:) INTEGER, ALLOCATABLE :: ipiv(:) CHARACTER (1) :: clabs(1), rlabs(1) ! .. Executable Statements .. WRITE (nout,*) 'F04CCF Example Program Results' WRITE (nout,*) FLUSH (nout) ! Skip heading in data file READ (nin,*) READ (nin,*) n, nrhs ldb = n ALLOCATE (b(ldb,nrhs),d(n),dl(n-1),du(n-1),du2(n-2),ipiv(n)) ! Read A and B from data file READ (nin,*) du(1:n-1) READ (nin,*) d(1:n) READ (nin,*) dl(1:n-1) 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 f04ccf(n,nrhs,dl,d,du,du2,ipiv,b,ldb,rcond,errbnd,ifail) IF (ifail==0) THEN ! Print solution, estimate of condition number and approximate ! error bound ierr = 0 CALL x04dbf('General',' ',n,nrhs,b,ldb,'Bracketed',' ','Solution', & 'Integer',rlabs,'Integer',clabs,80,0,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 x04dbf('General',' ',n,nrhs,b,ldb,'Bracketed',' ','Solution', & 'Integer',rlabs,'Integer',clabs,80,0,ierr) ELSE IF (ifail>0 .AND. ifail<=n) THEN ! The upper triangular matrix U is exactly singular. Print ! details of factorization WRITE (nout,*) 'Details of factorization' WRITE (nout,*) WRITE (nout,*) ' Second super-diagonal of U' WRITE (nout,99998) du2(1:n-2) WRITE (nout,*) WRITE (nout,*) ' First super-diagonal of U' WRITE (nout,99998) du(1:n-1) WRITE (nout,*) WRITE (nout,*) ' Main diagonal of U' WRITE (nout,99998) d(1:n) WRITE (nout,*) WRITE (nout,*) ' Multipliers' WRITE (nout,99998) dl(1:n-1) WRITE (nout,*) WRITE (nout,*) ' Vector of interchanges' WRITE (nout,99997) ipiv(1:n) ELSE WRITE (nout,99996) ifail END IF 99999 FORMAT (8X,1P,E9.1) 99998 FORMAT (4(1X,'(',F7.4,',',F7.4,')':)) 99997 FORMAT (1X,8I9) 99996 FORMAT (1X,' ** F04CCF returned with IFAIL = ',I5) END PROGRAM f04ccfe