! D02PE_T1W_F Example Program Text
! Mark 28.6 Release. NAG Copyright 2022.
Module d02pe_t1w_fe_mod
! D02PE_T1W_F Example Program Module:
! Parameters and User-defined Routines
! .. Use Statements ..
Use iso_c_binding, Only: c_ptr
Use nagad_library, Only: nagad_t1w_w_rtype, Operator (-)
! .. Implicit None Statement ..
Implicit None
! .. Accessibility Statements ..
Private
Public :: f
! .. Parameters ..
Integer, Parameter, Public :: liwsav = 130, n = 2, nin = 5, &
nout = 6, npts = 8
Integer, Parameter, Public :: lrwsav = 350 + 32*n
Contains
Subroutine f(ad_handle,t,n,y,yp,iuser,ruser)
! .. Implicit None Statement ..
Implicit None
! .. Scalar Arguments ..
Type (c_ptr), Intent (Inout) :: ad_handle
Type (nagad_t1w_w_rtype), Intent (In) :: t
Integer, Intent (In) :: n
! .. Array Arguments ..
Type (nagad_t1w_w_rtype), Intent (Inout) :: ruser(*)
Type (nagad_t1w_w_rtype), Intent (In) :: y(n)
Type (nagad_t1w_w_rtype), Intent (Out) :: yp(n)
Integer, Intent (Inout) :: iuser(*)
! .. Executable Statements ..
yp(1) = y(2)
yp(2) = -y(1)
Return
End Subroutine f
End Module d02pe_t1w_fe_mod
Program d02pe_t1w_fe
! D02PE_T1W_F Example Main Program
! .. Use Statements ..
Use d02pe_t1w_fe_mod, Only: f, liwsav, lrwsav, n, nin, nout, npts
Use iso_c_binding, Only: c_ptr
Use nagad_library, Only: d02pe_t1w_f, d02pq_t1w_f, d02pt_t1w_f, &
nagad_t1w_set_derivative, nagad_t1w_w_rtype, &
x10aa_t1w_f, x10ab_t1w_f, Assignment (=), &
Operator (+)
Use nag_library, Only: nag_wp
! .. Implicit None Statement ..
Implicit None
! .. Local Scalars ..
Type (c_ptr) :: ad_handle
Type (nagad_t1w_w_rtype) :: hnext, hs, te, tgot, tinc, tol, ts, &
twant, waste
Real (Kind=nag_wp) :: hstart, t, tend, tolr, tstart
Integer :: fevals, i, ifail, j, method, &
stepcost, stepsok
! .. Local Arrays ..
Type (nagad_t1w_w_rtype) :: ruser(1), th(n), y(n), ygot(n), &
yin(n), ymax(n), ypgot(n)
Type (nagad_t1w_w_rtype), Allocatable :: rwsav(:)
Real (Kind=nag_wp) :: dr(2), thresh(n), yinit(n), yr(n)
Integer :: iuser(1)
Integer, Allocatable :: iwsav(:)
! .. Intrinsic Procedures ..
Intrinsic :: real
! .. Executable Statements ..
Write (nout,*) 'D02PE_T1W_F Example Program Results'
Allocate (iwsav(liwsav),rwsav(lrwsav))
! Set initial conditions and input
! Skip heading in data file
Read (nin,*)
Read (nin,*) method
Read (nin,*) tstart, tend
Read (nin,*) yinit(1:n)
Read (nin,*) hstart
Read (nin,*) thresh(1:n)
! Set control for output
tinc = (tend-tstart)/real(npts,kind=nag_wp)
tolr = 1.0E-4_nag_wp
ts = tstart
te = tend
yin(1:n) = yinit(1:n)
tol = tolr
th(1:n) = thresh(1:n)
hs = hstart
Write (nout,99999) tolr
Write (nout,99998)
Write (nout,99997) tstart, yinit(1:n)
99999 Format (/,' Calculation with TOL = ',1P,E8.1)
99998 Format (/,' t y1 y2',/)
99997 Format (1X,F6.3,2(3X,F7.3))
! Create AD configuration data object
ifail = 0
Call x10aa_t1w_f(ad_handle,ifail)
Do i = 1, n
y(1:n) = yin(1:n)
Call nagad_t1w_set_derivative(y(i),1.0E0_nag_wp)
ifail = 0
Call d02pq_t1w_f(ad_handle,n,ts,te,y,tol,th,method,hs,iwsav,rwsav, &
ifail)
twant = tstart
Do j = 1, npts
twant = twant + tinc
ifail = 0
Call d02pe_t1w_f(ad_handle,f,n,twant,tgot,ygot,ypgot,ymax,iuser, &
ruser,iwsav,rwsav,ifail)
If (i==1) Then
t = tgot%value
yr(1:n) = ygot(1:n)%value
Write (nout,99997) t, yr(1:n)
End If
End Do
Call nagad_t1w_set_derivative(y(i),0.0E0_nag_wp)
dr(i) = ygot(1)%tangent
End Do
ifail = 0
Call d02pt_t1w_f(ad_handle,fevals,stepcost,waste,stepsok,hnext,iwsav, &
rwsav,ifail)
Write (nout,99996) fevals
99996 Format (/,' Cost of the integration in evaluations of F is',I6)
Write (nout,*)
Write (nout,*) ' Derivatives calculated: First order tangents'
Write (nout,*) ' Computational mode : algorithmic'
Write (nout,*)
Write (nout,*) ' Derivatives:'
Write (nout,99995) ' dy(t)/dy0 =', dr(1)
Write (nout,99995) ' dy(t)/dy0'' =', dr(2)
99995 Format (1X,A,1X,E12.5)
! Remove computational data object
ifail = 0
Call x10ab_t1w_f(ad_handle,ifail)
End Program d02pe_t1w_fe