Program f01ec_t1w_fe
! F01EC_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: f01ec_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
! .. Local Scalars ..
Type (c_ptr) :: ad_handle
Integer :: i, ifail, j, lda, n
! .. Local Arrays ..
Type (nagad_t1w_w_rtype), Allocatable :: a(:,:), a_in(:,:)
Real (Kind=nag_wp), Allocatable :: a_r(:,:)
! .. Executable Statements ..
Write (nout,*) 'F01EC_T1W_F Example Program Results'
Write (nout,*)
Flush (nout)
! Skip heading in data file
Read (nin,*)
Read (nin,*) n
lda = n
Allocate (a(lda,n),a_in(lda,n),a_r(lda,n))
! Read A from data file
Read (nin,*)(a_r(i,1:n),i=1,n)
a_in = a_r
! Create AD configuration data object
ifail = 0
Call x10aa_t1w_f(ad_handle,ifail)
Do i = 1, n
Call nagad_t1w_set_derivative(a_in(i,i),1.0_nag_wp)
a = a_in
! ifail: behaviour on error exit
! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
! Find exp( A )
Call f01ec_t1w_f(ad_handle,n,a,lda,ifail)
If (i==1) Then
a_r = a
! Print solution
Call x04caf('General',' ',n,n,a_r,lda,'Exp(A)',ifail)
End If
Do j = 1, n
a_r(i,j) = a(j,j)%tangent
End Do
a_in(i,i)%tangent = 0.0_nag_wp
End Do
Write (nout,*)
Write (nout,*) ' Derivatives calculated: First order tangents'
Write (nout,*) ' Computational mode : algorithmic'
Write (nout,*)
Write (nout,*) ' Derivatives of diagonal of exp(A) w.r.t. diagonal of A'
Write (nout,*)
Call x04caf('General',' ',n,n,a_r,n,' d(expA(i,i))/da(j,j)',ifail)
! Remove computational data object
Call x10ab_t1w_f(ad_handle,ifail)
End Program f01ec_t1w_fe