Program g10abfe

!     G10ABF Example Program Text

!     Mark 27.2 Release. NAG Copyright 2021.

!     .. Use Statements ..
      Use nag_library, Only: g10abf, g10zaf, nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
      Integer                          :: i, ifail, j, lcomm, ldc, lwt, n,     &
                                          nord, nrho
      Character (1)                    :: mode, weight
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: c(:,:), comm(:), df(:), h(:),        &
                                          res(:), rho(:), rss(:), wt(:),       &
                                          wwt(:), x(:), xord(:), y(:),         &
                                          yhat(:,:), yord(:)
      Integer, Allocatable             :: iwrk(:)
!     .. Executable Statements ..
      Write (nout,*) ' G10ABF Example Program Results'
      Write (nout,*)

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

!     Read in problem size and control parameters
      Read (nin,*) n, weight, nrho

      If (weight=='W' .Or. weight=='w') Then
        lwt = n
      Else
        lwt = 0
      End If
      lcomm = 9*n + 14
      ldc = n - 1
      Allocate (x(n),y(n),wt(lwt),xord(n),yord(n),wwt(n),yhat(n,nrho),         &
        c(ldc,3),res(n),h(n),comm(lcomm),iwrk(n),rho(nrho),rss(nrho),df(nrho))

!     Read in the smoothing parameters
      Read (nin,*) rho(1:nrho)

!     Read in data
      If (lwt>0) Then
        Read (nin,*)(x(i),y(i),wt(i),i=1,n)
      Else
        Read (nin,*)(x(i),y(i),i=1,n)
      End If

!     Reorder data into increasing X and remove tied observations, weighting
!     accordingly
      ifail = 0
      Call g10zaf(weight,n,x,y,wt,nord,xord,yord,wwt,rss(1),iwrk,ifail)

!     Fit cubic spline the first time
!     NB: These are weighted as G10ZAF creates weights
      ifail = 0
      mode = 'P'
      Call g10abf(mode,'W',nord,xord,yord,wwt,rho(1),yhat(1,1),c,ldc,rss(1),   &
        df(1),res,h,comm,ifail)

!     Fit cubic spline the remaining NRHO - 1 times
      mode = 'Q'
      Do i = 2, nrho
        ifail = 0
        Call g10abf(mode,'W',nord,xord,yord,wwt,rho(i),yhat(1,i),c,ldc,rss(i), &
          df(i),res,h,comm,ifail)
      End Do

!     Display results
      Write (nout,99999) 'Smoothing coefficient (rho) = ', rho(1:nrho)
      Write (nout,99998) 'Residual sum of squares     = ', rss(1:nrho)
      Write (nout,99998) 'Degrees of freedom          = ', df(1:nrho)
      Write (nout,*)
      Write (nout,*) '    X       Y                            Fitted Values'
      Do i = 1, nord
        Write (nout,99997) xord(i), yord(i), (yhat(i,j),j=1,nrho)
      End Do

99999 Format (1X,A,10(2X,F8.2))
99998 Format (1X,A,10(F10.3))
99997 Format (1X,2F8.4,14X,10(2X,F8.4))
    End Program g10abfe