! D01RL_A1W_F Example Program Text
! Mark 30.1 Release. NAG Copyright 2024.
Module d01rl_a1w_fe_mod
! .. Use Statements ..
Use nagad_library, Only: nagad_a1w_w_rtype, sqrt, Assignment (=), &
Operator (==), Operator (<), Operator (-), &
Operator (/)
Use nag_library, Only: nag_wp
! .. Implicit None Statement ..
Implicit None
! .. Accessibility Statements ..
Private
Public :: f
! .. Parameters ..
Integer, Parameter, Public :: nout = 6
Contains
Subroutine f(ad_handle,x,nx,fv,iflag,iuser,ruser,cpuser)
! .. Use Statements ..
Use, Intrinsic :: iso_c_binding, Only: c_ptr
! .. Scalar Arguments ..
Type (c_ptr), Intent (Inout) :: ad_handle
Type (c_ptr), Intent (In) :: cpuser
Integer, Intent (Inout) :: iflag
Integer, Intent (In) :: nx
! .. Array Arguments ..
Type (nagad_a1w_w_rtype), Intent (Out) :: fv(nx)
Type (nagad_a1w_w_rtype), Intent (Inout) :: ruser(*)
Type (nagad_a1w_w_rtype), Intent (In) :: x(nx)
Integer, Intent (Inout) :: iuser(*)
! .. Local Scalars ..
Integer :: i
! .. Executable Statements ..
iflag = 0
Do i = 1, nx
fv(i) = x(i) - 1.0_nag_wp/7.0_nag_wp
If (fv(i)==0.0_nag_wp) Then
! singular point has been hit
iflag = iflag + 1
ruser(iflag) = x(i)
Else If (fv(i)<0.0_nag_wp) Then
fv(i) = -fv(i)
End If
End Do
iuser(1) = iflag
! signal abort by setting iflag <0
If (iflag==0) Then
Do i = 1, nx
fv(i) = 1.0_nag_wp/sqrt(fv(i))
End Do
Else
iflag = -iflag
End If
Return
End Subroutine f
End Module d01rl_a1w_fe_mod
Program d01rl_a1w_fe
! D01RL_A1W_F Example Main Program
! .. Use Statements ..
Use d01rl_a1w_fe_mod, Only: f, nout
Use, Intrinsic :: iso_c_binding, Only: c_null_ptr, &
c_ptr
Use nagad_library, Only: d01rl_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
! .. Local Scalars ..
Type (nagad_a1w_w_rtype) :: a, abserr, b, epsabs, epsrel, result
Type (c_ptr) :: ad_handle, cpuser
Real (Kind=nag_wp) :: da, db
Integer :: ifail, liinfo, lrinfo, maxsub, npts
! .. Local Arrays ..
Type (nagad_a1w_w_rtype), Allocatable :: points(:), rinfo(:)
Type (nagad_a1w_w_rtype) :: ruser(20)
Integer, Allocatable :: iinfo(:)
Integer :: iuser(1)
! .. Intrinsic Procedures ..
Intrinsic :: max
! .. Executable Statements ..
Write (nout,*) 'D01RL_A1W_F Example Program Results'
! Create AD tape
Call nagad_a1w_ir_create
! Initialize AD types
a = 0.0_nag_wp
b = 1.0_nag_wp
epsabs = 0.0_nag_wp
epsrel = 1.0E-4_nag_wp
npts = 1
maxsub = 20
liinfo = 2*max(maxsub,npts) + npts + 4
lrinfo = 4*max(maxsub,npts) + npts + 6
Allocate (points(npts),rinfo(lrinfo),iinfo(liinfo))
points(1) = 1.0_nag_wp/7.0_nag_wp
iuser(1) = 0
ruser(1:20) = 0.0_nag_wp
cpuser = c_null_ptr
! 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(a)
Call nagad_a1w_ir_register_variable(b)
! Evaluate the integral using the AD routine
ifail = -1
Call d01rl_a1w_f(ad_handle,f,a,b,npts,points,epsabs,epsrel,maxsub, &
result,abserr,rinfo,iinfo,iuser,ruser,cpuser,ifail)
If (ifail<0) Then
If (ifail==-1) Then
Write (nout,99999) 'A user requested exit was issued from F '
Else
Write (nout,99999) 'The routine has failed with ifail = ', ifail
End If
Go To 100
99999 Format (1X,A,I0)
End If
! Print inputs and primal outputs
Write (nout,*)
Write (nout,99998) 'a ', 'lower limit of integration', a%value
Write (nout,99998) 'b ', 'upper limit of integration', b%value
Write (nout,99998) 'points(1)', 'given break-point', points(1)%value
Write (nout,99997) 'epsabs ', 'absolute accuracy requested', &
epsabs%value
Write (nout,99997) 'epsrel ', 'relative accuracy requested', &
epsrel%value
Write (nout,99995) 'maxsub ', 'max number of subintervals', maxsub
Write (nout,*)
If (ifail>=0) Then
Write (nout,99996) 'result ', 'approximation to the integral', &
result%value
Write (nout,99997) 'abserr ', 'estimate of the absolute error', &
abserr%value
Write (nout,99995) 'iinfo(1) ', 'number of subintervals used', &
iinfo(1)
End If
99998 Format (1X,A9,' - ',A32,' = ',F9.4)
99997 Format (1X,A9,' - ',A32,' = ',E9.2)
99996 Format (1X,A9,' - ',A32,' = ',F9.5)
99995 Format (1X,A9,' - ',A32,' = ',I4)
! Setup evaluation of derivatives via adjoints
Call nagad_a1w_inc_derivative(result,1.0E0_nag_wp)
Call nagad_a1w_ir_interpret_adjoint_sparse(ifail)
Write (nout,*)
Write (nout,*) ' Derivatives calculated: First order adjoints'
Write (nout,*) ' Computational mode : algorithmic'
! Get derivatives
da = nagad_a1w_get_derivative(a)
db = nagad_a1w_get_derivative(b)
Write (nout,*) ' Derivatives:'
Write (nout,99994) 'd/da(x) =', da
Write (nout,99994) 'd/db(x) =', db
99994 Format (1X,A15,1X,F10.5)
100 Continue
! Remove computational data object and tape
Call x10ab_a1w_f(ad_handle,ifail)
Call nagad_a1w_ir_remove
End Program d01rl_a1w_fe