Program f11xe_a1w_fe
! F11XE_A1W_F Example Program Text
! Mark 28.7 Release. NAG Copyright 2022.
! .. Use Statements ..
Use iso_c_binding, Only: c_ptr
Use nagad_library, Only: f11xe_a1w_f, nagad_a1w_get_derivative, &
nagad_a1w_inc_derivative, &
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, &
x10za_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, j, n, nnz
Character (1) :: check
! .. Local Arrays ..
Type (nagad_a1w_w_rtype), Allocatable :: a(:), x(:), y(:)
Real (Kind=nag_wp), Allocatable :: ar(:), dydx(:,:), yr(:)
Integer, Allocatable :: icol(:), irow(:)
! .. Executable Statements ..
Write (nout,*) 'F11XE_A1W_F Example Program Results'
! Skip heading in data file
Read (nin,*)
! Read order of matrix and number of nonzero entries
Read (nin,*) n
Read (nin,*) nnz
Allocate (a(nnz),x(n),y(n),icol(nnz),irow(nnz))
Allocate (ar(nnz),yr(n),dydx(n,n))
! Read the matrix A
Do i = 1, nnz
Read (nin,*) ar(i), irow(i), icol(i)
End Do
a(1:nnz) = ar(1:nnz)
! Read the vector x
Read (nin,*) yr(1:n)
x = yr
! Create AD tape
Call x10za_a1w_f
! 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(x)
! Calculate matrix-vector product
check = 'C'
ifail = 0
Call f11xe_a1w_f(ad_handle,n,nnz,a,irow,icol,check,x,y,ifail)
! Output results
Write (nout,*) ' Matrix-vector product'
Write (nout,99999)(y(i)%value,i=1,n)
Write (nout,*)
Write (nout,*) ' Derivatives calculated: First order adjoints'
Write (nout,*) ' Computational mode : algorithmic'
Write (nout,*)
Write (nout,*) ' Derivatives of Y w.r.t. X (A)'
Write (nout,*)
! Setup evaluation of derivatives via adjoints
Do i = 1, n
Call nagad_a1w_ir_zero_adjoints
Call nagad_a1w_inc_derivative(y(i),1.0_nag_wp)
ifail = 0
Call nagad_a1w_ir_interpret_adjoint_sparse(ifail)
! Get derivatives
Do j = 1, n
dydx(i,j) = nagad_a1w_get_derivative(x(j))
End Do
End Do
Call x04caf('General',' ',n,n,dydx,n,' dy(i)/dx(j)',ifail)
! Remove computational data object and tape
Call x10ab_a1w_f(ad_handle,ifail)
Call nagad_a1w_ir_remove
99999 Format (1X,1P,E16.4)
End Program f11xe_a1w_fe