Program e01bf_a1w_fe
! E01BF_A1W_F Example Program Text
! Mark 30.2 Release. NAG Copyright 2024.
! .. Use Statements ..
Use iso_c_binding, Only: c_ptr
Use nagad_library, Only: e01be_a1w_f, e01bf_a1w_f, &
nagad_a1w_get_derivative, &
nagad_a1w_inc_derivative, &
nagad_a1w_ir_create => x10za_a1w_f, &
nagad_a1w_ir_interpret_adjoint_sparse, &
nagad_a1w_ir_register_variable, &
nagad_a1w_ir_remove, nagad_a1w_w_rtype, &
x10aa_a1w_f, x10ab_a1w_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
Real (Kind=nag_wp) :: fr, xr
Integer :: i, ifail, m, n, r
! .. Local Arrays ..
Type (nagad_a1w_w_rtype), Allocatable :: d(:), f(:), pf(:), px(:), x(:)
Real (Kind=nag_wp), Allocatable :: df(:), dx(:)
! .. Executable Statements ..
Write (nout,*) 'E01BF_A1W_F Example Program Results'
! Skip heading in data file
Read (nin,*)
Read (nin,*) n
m = 1
Allocate (d(n),f(n),x(n),dx(n),df(n),px(m),pf(m))
! Create AD tape
Call nagad_a1w_ir_create
! Initialize x and f arrays using data
Do r = 1, n
Read (nin,*) xr, fr
x(r) = xr
f(r) = fr
End Do
! Create AD configuration data object
ifail = 0
Call x10aa_a1w_f(ad_handle,ifail)
! Register variables to differentiate w.r.t.
Call nagad_a1w_ir_register_variable(x)
Call nagad_a1w_ir_register_variable(f)
! Call the AD routine
ifail = 0
Call e01be_a1w_f(ad_handle,n,x,f,d,ifail)
! Evaluate interpolant and derivatives at a mid-point
px(1) = 0.5_nag_wp*(x(n/2)%value+x(n/2+1)%value)
Call e01bf_a1w_f(ad_handle,n,x,f,d,m,px,pf,ifail)
Write (nout,*)
Write (nout,*) ' Derivatives calculated: First order adjoints'
Write (nout,*) ' Computational mode : algorithmic'
! Get derivative of interpolated value w.r.t data points and values
Call nagad_a1w_inc_derivative(pf(1),1.0_nag_wp)
Call nagad_a1w_ir_interpret_adjoint_sparse(ifail)
dx(1:n) = nagad_a1w_get_derivative(x)
df(1:n) = nagad_a1w_get_derivative(f)
Write (nout,*)
Write (nout,99999) 'Interpolated value at x = ', px(1)%value, ' is: ', &
pf(1)%value
99999 Format (1X,A,F7.3,A,E12.5)
Write (nout,*)
Write (nout,*) ' Derivatives of interpolated value w.r.t. x and f:'
Write (nout,*)
Write (nout,*) ' i d/dx d/df'
Do i = 1, n
Write (nout,99998) i, dx(i), df(i)
End Do
99998 Format (1X,I5,1X,E12.5,1X,E12.5)
! Remove computational data object and tape
ifail = 0
Call x10ab_a1w_f(ad_handle,ifail)
Call nagad_a1w_ir_remove
End Program e01bf_a1w_fe