Program f06pa_t1w_fe
! F06PA_T1W_F Example Program Text
! Mark 29.3 Release. NAG Copyright 2023.
! .. Use Statements ..
Use iso_c_binding, Only: c_ptr
Use nagad_library, Only: f06pa_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
Type (nagad_t1w_w_rtype) :: alpha, beta
Real (Kind=nag_wp) :: alphar, betar
Integer :: i, ifail, lda, m, n
! .. Local Arrays ..
Type (nagad_t1w_w_rtype), Allocatable :: a(:,:), b(:), y(:), y_in(:)
Real (Kind=nag_wp), Allocatable :: ar(:,:), br(:), da(:), db(:), yr(:)
! .. Executable Statements ..
Write (nout,*) 'F06PA_T1W_F Example Program Results'
Write (nout,*)
! Skip heading in data file
Read (nin,*)
Read (nin,*) m, n
Read (nin,*) alphar, betar
alpha = alphar
beta = betar
lda = m
Allocate (a(lda,n),b(m),y(n),y_in(n))
Allocate (ar(lda,n),br(m),yr(n),da(n),db(n))
! Read the m by n matrix A from data file
Read (nin,*)(ar(i,1:n),i=1,m)
! Read the vector to be multiplied by A
Read (nin,*) br(1:m)
yr = 1.0_nag_wp
y_in = yr
! Create AD configuration data object
ifail = 0
Call x10aa_t1w_f(ad_handle,ifail)
a = ar
b = br
Call nagad_t1w_set_derivative(alpha,1.0_nag_wp)
y(1:n) = y_in(1:n)
ifail = 0
Call f06pa_t1w_f(ad_handle,'T',m,n,alpha,a,lda,b,1,beta,y,1,ifail)
Write (nout,*)
Write (nout,*) 'Product solution y = beta*y + alpha*A^T*b:'
yr = y
Write (nout,99999) yr(1:n)
99999 Format (4X,F11.4)
! Get derivatives
da(1:n) = y(1:n)%tangent
alpha = alphar
beta = betar
Call nagad_t1w_set_derivative(beta,1.0_nag_wp)
y(1:n) = y_in(1:n)
ifail = 0
Call f06pa_t1w_f(ad_handle,'T',m,n,alpha,a,lda,b,1,beta,y,1,ifail)
db(1:n) = y(1:n)%tangent
Write (nout,*)
Write (nout,*) ' Derivatives calculated: First order tangentss'
Write (nout,*) ' Computational mode : algorithmic'
Write (nout,*)
Write (nout,*) ' Derivatives of y w.r.t. alpha and beta'
Write (nout,*)
! Setup evaluation of derivatives via adjoints
Call x04caf('General',' ',1,n,da,1,' dy/dalpha',ifail)
Write (nout,*)
Call x04caf('General',' ',1,n,db,1,' dy/dbeta',ifail)
! Remove computational data object
Call x10ab_t1w_f(ad_handle,ifail)
End Program f06pa_t1w_fe