Program f07fd_a1w_fe
! F07FD_A1W_F Example Program Text
! Mark 29.2 Release. NAG Copyright 2023.
! .. Use Statements ..
Use iso_c_binding, Only: c_ptr
Use nagad_library, Only: f07fd_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
! .. Local Scalars ..
Type (c_ptr) :: ad_handle
Integer :: i, ifail, info, lda, n
Character (1) :: uplo
! .. Local Arrays ..
Type (nagad_a1w_w_rtype), Allocatable :: a(:,:), ax(:,:)
Real (Kind=nag_wp), Allocatable :: ar(:,:), ddda(:,:)
! .. Executable Statements ..
Write (nout,*) 'F07FD_A1W_F Example Program Results'
! Skip heading in data file
Read (nin,*)
Read (nin,*) n
lda = n
Allocate (a(lda,n),ax(lda,n))
Allocate (ar(lda,n),ddda(n,n))
! Read A from data file
ar = 0.0_nag_wp
Read (nin,*) uplo
If (uplo=='U') Then
Read (nin,*)(ar(i,i:n),i=1,n)
Else If (uplo=='L') Then
Read (nin,*)(ar(i,1:i),i=1,n)
End If
a = ar
! 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(a)
ax = a
! Factorize A
! The NAG name equivalent of dpotrf_a1w is f07fd_a1w_f
Call f07fd_a1w_f(ad_handle,uplo,n,ax,lda,info)
Write (nout,*)
Flush (nout)
If (info==0) Then
! Print factor
ar(1:n,1:n) = ax(1:n,1:n)%value
! ifail: behaviour on error exit
! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
Call x04caf(uplo,'Nonunit',n,n,ar,lda,'Factor',ifail)
Else
Write (nout,*) 'A is not positive definite'
Go To 100
End If
Write (nout,*)
Write (nout,*) ' Derivatives calculated: First order adjoints'
Write (nout,*) ' Computational mode : algorithmic'
Write (nout,*)
Write (nout,*) ' Derivatives of diagonal of L w.r.t. first column of A:'
! Setup evaluation of derivatives via adjoints
Do i = 1, n
Call nagad_a1w_ir_zero_adjoints
Call nagad_a1w_inc_derivative(ax(i,i),1.0_nag_wp)
ifail = 0
Call nagad_a1w_ir_interpret_adjoint_sparse(ifail)
! Get derivatives
ddda(i,1:n) = nagad_a1w_get_derivative(a(1:n,1))
End Do
Call x04caf('General',' ',n,n,ddda,n,'',ifail)
! Remove computational data object and tape
100 Call x10ab_a1w_f(ad_handle,ifail)
Call nagad_a1w_ir_remove
End Program f07fd_a1w_fe