Program f07ca_t1w_fe
! F07CA_T1W_F Example Program Text
! Mark 30.1 Release. NAG Copyright 2024.
! .. Use Statements ..
Use iso_c_binding, Only: c_ptr
Use nagad_library, Only: f07ca_t1w_f, nagad_t1w_set_derivative, &
nagad_t1w_w_rtype, x10aa_t1w_f, x10ab_t1w_f, &
Assignment (=)
Use nag_library, Only: nag_wp, x04caf
! .. Implicit None Statement ..
Implicit None
! .. Parameters ..
Integer, Parameter :: nin = 5, nout = 6, nrhs = 1
! .. Local Scalars ..
Type (c_ptr) :: ad_handle
Integer :: i, ifail, k, n
! .. Local Arrays ..
Type (nagad_t1w_w_rtype), Allocatable :: b(:), d(:), df(:), dl(:), &
dlf(:), du(:), duf(:), x(:)
Real (Kind=nag_wp), Allocatable :: dxdb(:,:), dxdd(:,:), dxdl(:,:), &
dxdu(:,:)
! .. Executable Statements ..
Write (nout,*) 'F07CA_T1W_F Example Program Results'
Write (nout,*)
! Skip heading in data file
Read (nin,*)
Read (nin,*) n
Allocate (b(n),d(n),dl(n-1),du(n-1))
Allocate (x(n),df(n),dlf(n-1),duf(n-1))
Allocate (dxdb(n,n),dxdd(n,n),dxdl(n,n-1),dxdu(n,n-1))
! Read the tridiagonal matrix A and the right hand side B from
! data file and initialize AD arrays
Read (nin,*) dxdu(1:n-1,1)
Read (nin,*) dxdd(1:n,1)
Read (nin,*) dxdl(1:n-1,1)
Read (nin,*) dxdb(1:n,1)
du(1:n-1) = dxdu(1:n-1,1)
d(1:n) = dxdd(1:n,1)
dl(1:n-1) = dxdl(1:n-1,1)
b(1:n) = dxdb(1:n,1)
! Create AD configuration data object
ifail = 0
Call x10aa_t1w_f(ad_handle,ifail)
Do i = 1, 4*n - 2
If (i<n) Then
k = i
Call nagad_t1w_set_derivative(du(k),1.0_nag_wp)
Else If (i<2*n) Then
k = i - n + 1
Call nagad_t1w_set_derivative(d(k),1.0_nag_wp)
Else If (i<3*n-1) Then
k = i - 2*n + 1
Call nagad_t1w_set_derivative(dl(k),1.0_nag_wp)
Else
k = i - 3*n + 2
Call nagad_t1w_set_derivative(b(k),1.0_nag_wp)
End If
dlf = dl
df = d
duf = du
x = b
! Solve the equations Ax = b for x
ifail = 0
Call f07ca_t1w_f(ad_handle,n,nrhs,dlf,df,duf,x,n,ifail)
If (i<n) Then
du(k)%tangent = 0.0_nag_wp
dxdu(1:n,k) = x(1:n)%tangent
Else If (i<2*n) Then
d(k)%tangent = 0.0_nag_wp
dxdd(1:n,k) = x(1:n)%tangent
Else If (i<3*n-1) Then
dl(k)%tangent = 0.0_nag_wp
dxdl(1:n,k) = x(1:n)%tangent
Else
b(k)%tangent = 0.0_nag_wp
dxdb(1:n,k) = x(1:n)%tangent
End If
End Do
! Print primal solution
Write (nout,*) 'Solution'
Write (nout,99999) x(1:n)%value
99999 Format (1X,7F11.4)
Write (nout,*)
Write (nout,*) ' Derivatives calculated: First order tangents'
Write (nout,*) ' Computational mode : algorithmic'
Write (nout,*)
Write (nout,*) ' Derivatives of solution w.r.t. inputs:'
Write (nout,*)
Call x04caf('General',' ',n,n-1,dxdu,n,'dx/d(du)',ifail)
Write (nout,*)
Call x04caf('General',' ',n,n,dxdd,n,'dx/d(d)',ifail)
Write (nout,*)
Call x04caf('General',' ',n,n-1,dxdl,n,'dx/d(dl)',ifail)
Write (nout,*)
Call x04caf('General',' ',n,n,dxdb,n,'dx/d(db)',ifail)
! Remove computational data object
Call x10ab_t1w_f(ad_handle,ifail)
End Program f07ca_t1w_fe