Program f07ue_a1w_fe
! F07UE_A1W_F Example Program Text
! Mark 29.0 Release. NAG Copyright 2023.
! .. Use Statements ..
Use iso_c_binding, Only: c_ptr
Use nagad_library, Only: f07ue_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_ir_zero_adjoints &
, nagad_a1w_w_rtype, x10aa_a1w_f, x10ab_a1w_f, &
Assignment (=)
Use nag_library, Only: nag_wp, x04caf
! .. Implicit None Statement ..
Implicit None
! .. Parameters ..
Integer, Parameter :: nin = 5, nout = 6
Character (1), Parameter :: diag = 'N', trans = 'N'
! .. Local Scalars ..
Type (c_ptr) :: ad_handle
Integer :: i, ifail, j, ld, ldb, n, nrhs
Character (1) :: uplo
! .. Local Arrays ..
Type (nagad_a1w_w_rtype), Allocatable :: a(:), ax(:), b(:,:), x(:,:)
Real (Kind=nag_wp), Allocatable :: ar(:), dxdb(:,:), xr(:,:)
! .. Executable Statements ..
Write (nout,*) 'F07UE_A1W_F Example Program Results'
! Skip heading in data file
Read (nin,*)
Read (nin,*) n, nrhs
ld = (n*(n+1))/2
ldb = n
Allocate (a(ld),b(ldb,nrhs),ax(ld),x(ldb,nrhs))
Allocate (ar(ld),xr(ldb,nrhs),dxdb(n,n))
! Read A and B from data file
ar = 0.0_nag_wp
Read (nin,*) uplo
If (uplo=='U') Then
Read (nin,*)((ar(i+j*(j+1)/2),j=1,i),i=1,n)
Else If (uplo=='L') Then
Read (nin,*)((ar(i+(2*n-j)*(j-1)/2),j=1,i),i=1,n)
End If
a = ar
Read (nin,*)(xr(i,1:nrhs),i=1,n)
b = xr
! Create AD tape
Call nagad_a1w_ir_create
! 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(b)
ax = a
x = b
! Compute solution
Call f07ue_a1w_f(ad_handle,uplo,trans,diag,n,nrhs,ax,x,ldb,ifail)
! Print solution
xr(1:n,1:nrhs) = x(1:n,1:nrhs)%value
! ifail: behaviour on error exit
! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
Call x04caf('General',' ',n,nrhs,xr,ldb,'Solution(s)',ifail)
Write (nout,*)
Write (nout,*) ' Derivatives calculated: First order adjoints'
Write (nout,*) ' Computational mode : algorithmic'
Write (nout,*)
Write (nout,*) ' Derivatives of solution x(:,1) w.r.t. b(:,1)'
Write (nout,*) ' (i.e. The inverse of A) :'
! Setup evaluation of derivatives via adjoints
Do i = 1, n
Call nagad_a1w_ir_zero_adjoints
Call nagad_a1w_inc_derivative(x(i,1),1.0_nag_wp)
ifail = 0
Call nagad_a1w_ir_interpret_adjoint_sparse(ifail)
! Get derivatives
dxdb(i,1:n) = nagad_a1w_get_derivative(b(1:n,1))
End Do
Call x04caf('General',' ',n,n,dxdb,n,'',ifail)
! Remove computational data object and tape
Call x10ab_a1w_f(ad_handle,ifail)
Call nagad_a1w_ir_remove
End Program f07ue_a1w_fe