Program f11jpfe

!     F11JPF Example Program Text

!     Mark 29.1 Release. NAG Copyright 2023.

!     .. Use Statements ..
      Use nag_library, Only: f11jnf, f11jpf, nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: dscale, dtol
      Integer                          :: i, ifail, la, lfill, liwork, n, nnz, &
                                          nnzc, npivm
      Character (1)                    :: check, mic, pstrat
!     .. Local Arrays ..
      Complex (Kind=nag_wp), Allocatable :: a(:), x(:), y(:)
      Integer, Allocatable             :: icol(:), ipiv(:), irow(:), istr(:),  &
                                          iwork(:)
!     .. Executable Statements ..
      Write (nout,*) 'F11JPF Example Program Results'
!     Skip heading in data file
      Read (nin,*)

!     Read order of matrix and number of nonzero entries

      Read (nin,*) n
      Read (nin,*) nnz
      la = 3*nnz
      liwork = 2*la + 7*n + 1
      Allocate (a(la),x(n),y(n),icol(la),ipiv(n),irow(la),istr(n+1),           &
        iwork(liwork))

!     Read the matrix A

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

!     Read the vector y

      Read (nin,*) y(1:n)

!     Calculate Cholesky factorization

      lfill = -1
      dtol = 0.0E0_nag_wp
      mic = 'N'
      dscale = 0.0E0_nag_wp
      pstrat = 'M'

!     ifail: behaviour on error exit
!             =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
      ifail = 0
      Call f11jnf(n,nnz,a,la,irow,icol,lfill,dtol,mic,dscale,pstrat,ipiv,istr, &
        nnzc,npivm,iwork,liwork,ifail)

!     Check the output value of NPIVM

      If (npivm/=0) Then

        Write (nout,*) 'Factorization is not complete'

      Else

!       Solve P L D L^H P^T x = y

        check = 'C'

        ifail = 0
        Call f11jpf(n,a,la,irow,icol,ipiv,istr,check,y,x,ifail)

!       Output results

        Write (nout,*) 'Solution of linear system'
        Write (nout,99999) x(1:n)
      End If

99999 Format (1X,'(',E16.4,',',E16.4,')')
    End Program f11jpfe