Program f11mefe

!     F11MEF Example Program Text

!     Mark 28.6 Release. NAG Copyright 2022.

!     .. Use Statements ..
      Use nag_library, Only: f11mdf, f11mef, nag_wp, x04cbf
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Real (Kind=nag_wp), Parameter    :: one = 1.E0_nag_wp
      Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: flop, thresh
      Integer                          :: i, ifail, n, nnz, nnzl, nnzu, nzlmx, &
                                          nzlumx, nzumx
      Character (1)                    :: spec
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: a(:), lval(:), uval(:)
      Integer, Allocatable             :: icolzp(:), il(:), iprm(:),           &
                                          irowix(:), iu(:)
      Character (1)                    :: clabs(1), rlabs(1)
!     .. Executable Statements ..
      Write (nout,*) 'F11MEF Example Program Results'
      Flush (nout)
!     Skip heading in data file
      Read (nin,*)

!     Read order of matrix

      Read (nin,*) n

      Allocate (icolzp(n+1),iprm(7*n))

!     Read the matrix A

      Read (nin,*) icolzp(1:n+1)
      nnz = icolzp(n+1) - 1

      Allocate (a(nnz),lval(8*nnz),uval(8*nnz),il(7*n+8*nnz+4),irowix(nnz),    &
        iu(2*n+8*nnz+1))

      Do i = 1, nnz
        Read (nin,*) a(i), irowix(i)
      End Do

!     Calculate COLAMD permutation

      spec = 'M'

!     ifail: behaviour on error exit
!             =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
      ifail = 0
      Call f11mdf(spec,n,icolzp,irowix,iprm,ifail)

!     Factorise

      thresh = one
      ifail = 0
      nzlmx = 8*nnz
      nzlumx = 8*nnz
      nzumx = 8*nnz
      Call f11mef(n,irowix,a,iprm,thresh,nzlmx,nzlumx,nzumx,il,lval,iu,uval,   &
        nnzl,nnzu,flop,ifail)

!     Output results

      Write (nout,99999)
      Write (nout,99998) nnzl + nnzu - n
      Flush (nout)

      Call x04cbf('G','X',1,10,lval,1,'F7.2','Factor elements in LVAL','N',    &
        rlabs,'N',clabs,80,0,ifail)
      Call x04cbf('G','X',1,4,uval,1,'F7.2','Factor elements in UVAL','N',     &
        rlabs,'N',clabs,80,0,ifail)

99999 Format (1X,/,1X,'Number of nonzeros in factors (excluding unit',         &
        ' diagonal)')
99998 Format (1X,I8)
    End Program f11mefe