Program e02gcfe

!     E02GCF Example Program Text

!     Mark 27.3 Release. NAG Copyright 2021.

!     .. Use Statements ..
      Use nag_library, Only: e02gcf, nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: n = 3, nin = 5, nout = 6
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: relerr, resmax, t, tol
      Integer                          :: i, ifail, irank, iter, lda, m, sda
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: a(:,:), b(:), x(:)
!     .. Intrinsic Procedures ..
      Intrinsic                        :: exp
!     .. Executable Statements ..
      Write (nout,*) 'E02GCF Example Program Results'

!     Skip heading in data file
      Read (nin,*)

      Read (nin,*) m
      lda = n + 3
      sda = m + 1
      Allocate (a(lda,sda),b(m),x(n))

      Do i = 1, m
        Read (nin,*) t, b(i)
        a(1,i) = exp(t)
        a(2,i) = exp(-t)
        a(3,i) = 1.0E0_nag_wp
      End Do

      tol = 0.0E0_nag_wp
      relerr = 0.0E0_nag_wp

      ifail = -1
      Call e02gcf(m,n,sda,lda,a,b,tol,relerr,x,resmax,irank,iter,ifail)

      Select Case (ifail)
      Case (0,1)
        Write (nout,*)
        Write (nout,99999) 'RESMAX = ', resmax, '  Rank = ', irank,            &
          '  Iterations = ', iter, '  IFAIL =', ifail
        Write (nout,*)
        Write (nout,*) 'Solution'
        Write (nout,99998) x(1:n)
      End Select

99999 Format (1X,A,E10.2,3(A,I5))
99998 Format (1X,6F10.4)
    End Program e02gcfe