! E01BA_A1W_F Example Program Text
! Mark 30.1 Release. NAG Copyright 2024.
Program e01ba_a1w_fe
! .. Use Statements ..
Use iso_c_binding, Only: c_ptr
Use nagad_library, Only: e01ba_a1w_f, e02bb_a1w_f, exp, &
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 :: m = 7, nout = 6
Integer, Parameter :: lck = m + 4
Integer, Parameter :: lwrk = 6*m + 16
Real (Kind=nag_wp), Parameter :: xc(m) = (/0.0_nag_wp,0.2_nag_wp, &
0.4_nag_wp,0.6_nag_wp,0.75_nag_wp, &
0.9_nag_wp,1.0_nag_wp/)
! .. Local Scalars ..
Type (c_ptr) :: ad_handle
Type (nagad_a1w_w_rtype) :: fit, xint
Integer :: ifail, j
! .. Local Arrays ..
Type (nagad_a1w_w_rtype) :: c(lck), lamda(lck), wrk(lwrk), x(m), &
y(m)
Real (Kind=nag_wp) :: dx(m), dy(m)
! .. Executable Statements ..
Write (nout,*) 'E01BA_A1W_F Example Program Results'
x(1:m) = xc(1:m)
y(1:m) = exp(x(1:m))
! Create AD tape
Call nagad_a1w_ir_create
! Create AD configuration data object and set computational mode
ifail = 0
Call x10aa_a1w_f(ad_handle,ifail)
ifail = 0
! Register variables to differentiate w.r.t.
Call nagad_a1w_ir_register_variable(x)
Call nagad_a1w_ir_register_variable(y)
c = 0.0_nag_wp
! Call AD routine
ifail = 0
Call e01ba_a1w_f(ad_handle,m,x,y,lamda,c,lck,wrk,lwrk,ifail)
! Call Use spline computed by e01ba to fit value at x = 0.5 using e02bb
xint = 0.5_nag_wp
ifail = 0
Call e02bb_a1w_f(ad_handle,lck,lamda,c,xint,fit,ifail)
Write (nout,*)
Write (nout,99999) xint%value, fit%value
99999 Format (1X,' Value of fitted spline at x = ',F6.2,', is: ',F7.4)
! Setup evaluation of derivatives via adjoints
Call nagad_a1w_inc_derivative(fit,1.0_nag_wp)
ifail = 0
Call nagad_a1w_ir_interpret_adjoint_sparse(ifail)
Write (nout,*)
Write (nout,*) ' Derivatives calculated: First order adjoints'
Write (nout,*) ' Computational mode : algorithmic'
! Get derivatives
dx = nagad_a1w_get_derivative(x)
dy = nagad_a1w_get_derivative(y)
Write (nout,*)
Write (nout,*) ' Derivatives of fitted value w.r.t. data points:'
Write (nout,*) ' j d/dx(j) d/y(j)'
Do j = 1, m
Write (nout,99998) j, dx(j), dy(j)
End Do
99998 Format (1X,I3,1X,E12.5,1X,E12.5)
! Remove computational data object and tape
Call x10ab_a1w_f(ad_handle,ifail)
Call nagad_a1w_ir_remove
End Program e01ba_a1w_fe