Program g02dkfe

!     G02DKF Example Program Text

!     Mark 27.3 Release. NAG Copyright 2021.

!     .. Use Statements ..
      Use nag_library, Only: g02daf, g02dkf, nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: rss, tol
      Integer                          :: i, iconst, idf, ifail, ip, irank,    &
                                          ldc, ldq, ldx, lwk, lwt, m, n, tlwk
      Logical                          :: svd
      Character (1)                    :: mean, weight
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: b(:), c(:,:), cov(:), h(:), p(:),    &
                                          q(:,:), res(:), se(:), wk(:), wt(:), &
                                          x(:,:), y(:)
      Integer, Allocatable             :: isx(:)
!     .. Intrinsic Procedures ..
      Intrinsic                        :: count
!     .. Executable Statements ..
      Write (nout,*) 'G02DKF Example Program Results'
      Write (nout,*)

!     Skip heading in data file
      Read (nin,*)
      Read (nin,*) n, m, weight, mean

!     Read in data
      If (weight=='W' .Or. weight=='w') Then
        lwt = n
      Else
        lwt = 0
      End If
      ldx = n
      Allocate (x(ldx,m),isx(m),y(n),wt(lwt))

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

!     Read in variable inclusion flags
      Read (nin,*) isx(1:m)

!     Calculate IP
      ip = count(isx>0)
      If (mean=='M' .Or. mean=='m') Then
        ip = ip + 1
      End If

      lwk = 5*(ip-1) + ip*ip
      ldq = n
      ldc = ip
      Allocate (b(ip),se(ip),cov(ip*(ip+1)/2),res(n),h(n),q(ldq,ip+1),p(2*ip+  &
        ip*ip),wk(lwk),c(ldc,ip))

!     Use suggested value for tolerance
      tol = 0.000001E0_nag_wp

!     Fit general linear regression model
      ifail = 0
      Call g02daf(mean,weight,n,x,ldx,m,isx,ip,y,wt,rss,idf,b,se,cov,res,h,q,  &
        ldq,svd,irank,p,tol,wk,ifail)

!     Display the initial estimates
      Write (nout,*) 'Estimates from G02DAF'
      Write (nout,*)
      Write (nout,99999) 'Residual sum of squares = ', rss
      Write (nout,99998) 'Degrees of freedom = ', idf
      Write (nout,*)
      Write (nout,*) 'Variable    Parameter estimate   Standard error'
      Write (nout,*)
      Write (nout,99997)(i,b(i),se(i),i=1,ip)

!     Read in constraints
      iconst = ip - irank
      Read (nin,*)(c(i,1:iconst),i=1,ip)

      tlwk = 2*ip*ip + ip*iconst + 2*iconst*iconst + 4*iconst
      If (tlwk>lwk) Then
!       Reallocate workspace
        Deallocate (wk)
        Allocate (wk(tlwk))
      End If

!     Re-estimate the parameters given the constraints
      ifail = 0
      Call g02dkf(ip,iconst,p,c,ldc,b,rss,idf,se,cov,wk,ifail)

!     Display the results
      Write (nout,*)
      Write (nout,*) 'Estimates from G02DKF using constraints'
      Write (nout,*)
      Write (nout,*) 'Variable    Parameter estimate   Standard error'
      Write (nout,*)
      Write (nout,99997)(i,b(i),se(i),i=1,ip)

99999 Format (1X,A,E13.3)
99998 Format (1X,A,I4)
99997 Format (1X,I6,2E20.3)
    End Program g02dkfe