Program g01fb_t1w_fe

!     G01FB_T1W_F Example Program Text
!     Mark 27.2 Release. NAG Copyright 2021.

!     .. Use Statements ..
      Use iso_c_binding, Only: c_ptr
      Use nagad_library, Only: g01fb_t1w_f, nagad_t1w_set_derivative,          &
                               nagad_t1w_w_rtype, x10aa_t1w_f, x10ab_t1w_f,    &
                               Assignment (=)
      Use nag_library, Only: nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
      Type (c_ptr)                     :: ad_handle
      Type (nagad_t1w_w_rtype)         :: df, p, x
      Real (Kind=nag_wp)               :: dfr, dxdf, dxdp, pr
      Integer                          :: i, ifail, n
      Character (1)                    :: tail
!     .. Executable Statements ..
      Write (nout,*) 'G01FB_T1W_F Example Program Results'

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

      Write (nout,*)
      Write (nout,*) ' deviates and derivatives'
      Write (nout,*)
      Write (nout,*) ' tail   p            df           x            dx/dp' // &
        '       dx/ddf'

!     Create AD configuration data object
      ifail = 0
      Call x10aa_t1w_f(ad_handle,ifail)

      Do i = 1, n

        Read (nin,*) pr, dfr, tail
        p = pr
        df = dfr
        Call nagad_t1w_set_derivative(p,1.0_nag_wp)

        ifail = 0
        Call g01fb_t1w_f(ad_handle,tail,p,df,x,ifail)

        dxdp = x%tangent

        p = pr
        df = dfr
        Call nagad_t1w_set_derivative(df,1.0_nag_wp)

        ifail = 0
        Call g01fb_t1w_f(ad_handle,tail,p,df,x,ifail)
        dxdf = x%tangent

        Write (nout,99999) tail, p%value, df%value, x%value, dxdp, dxdf
      End Do
99999 Format (1X,A5,1P,5E13.4)

!     Remove computational data object
      Call x10ab_t1w_f(ad_handle,ifail)

    End Program g01fb_t1w_fe