NAG Library Manual, Mark 27.2
```    Program f08ysfe

!     F08YSF Example Program Text

!     Mark 27.2 Release. NAG Copyright 2021.

!     .. Use Statements ..
Use nag_library, Only: f06uaf, nag_wp, x02ajf, x04dbf, zggsvp, ztgsja
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
Real (Kind=nag_wp)               :: eps, tola, tolb
Integer                          :: i, ifail, info, irank, j, k, l, lda, &
ldb, ldq, ldu, ldv, m, n, ncycle, p
!     .. Local Arrays ..
Complex (Kind=nag_wp), Allocatable :: a(:,:), b(:,:), q(:,:), tau(:),    &
u(:,:), v(:,:), work(:)
Real (Kind=nag_wp), Allocatable  :: alpha(:), beta(:), rwork(:)
Integer, Allocatable             :: iwork(:)
Character (1)                    :: clabs(1), rlabs(1)
!     .. Intrinsic Procedures ..
Intrinsic                        :: max, real
!     .. Executable Statements ..
Write (nout,*) 'F08YSF Example Program Results'
Write (nout,*)
Flush (nout)

!     Skip heading in data file
lda = m
ldb = p
ldq = n
ldu = m
ldv = p
Allocate (a(lda,n),b(ldb,n),q(ldq,n),tau(n),u(ldu,m),v(ldv,p),           &
work(m+3*n+p),alpha(n),beta(n),rwork(2*n),iwork(n))

!     Read the m by n matrix A and p by n matrix B from data file

!     Compute tola and tolb as
!         tola = max(m,n)*norm(A)*macheps
!         tolb = max(p,n)*norm(B)*macheps

eps = x02ajf()
tola = real(max(m,n),kind=nag_wp)*f06uaf('One-norm',m,n,a,lda,rwork)*eps
tolb = real(max(p,n),kind=nag_wp)*f06uaf('One-norm',p,n,b,ldb,rwork)*eps

!     Compute the factorization of (A, B)
!         (A = U1*S*(Q1**H), B = V1*T*(Q1**H))

!     The NAG name equivalent of zggsvp is f08vsf
Call zggsvp('U','V','Q',m,p,n,a,lda,b,ldb,tola,tolb,k,l,u,ldu,v,ldv,q,   &
ldq,iwork,rwork,tau,work,info)

!     Compute the generalized singular value decomposition of (A, B)
!         (A = U*D1*(0 R)*(Q**H), B = V*D2*(0 R)*(Q**H))

!     The NAG name equivalent of ztgsja is f08ysf
Call ztgsja('U','V','Q',m,p,n,k,l,a,lda,b,ldb,tola,tolb,alpha,beta,u,    &
ldu,v,ldv,q,ldq,work,ncycle,info)

If (info==0) Then

!       Print solution

irank = k + l
Write (nout,*) 'Number of infinite generalized singular values (K)'
Write (nout,99999) k
Write (nout,*) 'Number of finite generalized singular values (L)'
Write (nout,99999) l
Write (nout,*) ' Effective Numerical rank of (A**T B**T)**T (K+L)'
Write (nout,99999) irank
Write (nout,*)
Write (nout,*) 'Finite generalized singular values'
Write (nout,99998)(alpha(j)/beta(j),j=k+1,irank)
Write (nout,*)
Flush (nout)

!       ifail: behaviour on error exit
!              =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
Call x04dbf('General',' ',m,m,u,ldu,'Bracketed','1P,E12.4',            &
'Unitary matrix U','Integer',rlabs,'Integer',clabs,80,0,ifail)

Write (nout,*)
Flush (nout)

Call x04dbf('General',' ',p,p,v,ldv,'Bracketed','1P,E12.4',            &
'Unitary matrix V','Integer',rlabs,'Integer',clabs,80,0,ifail)

Write (nout,*)
Flush (nout)

Call x04dbf('General',' ',n,n,q,ldq,'Bracketed','1P,E12.4',            &
'Unitary matrix Q','Integer',rlabs,'Integer',clabs,80,0,ifail)

Write (nout,*)
Flush (nout)

Call x04dbf('Upper triangular','Non-unit',irank,irank,a(1,n-irank+1),  &
lda,'Bracketed','1P,E12.4','Nonsingular upper triangular matrix R',  &
'Integer',rlabs,'Integer',clabs,80,0,ifail)

Write (nout,*)
Write (nout,*) 'Number of cycles of the Kogbetliantz method'
Write (nout,99999) ncycle
Else
Write (nout,99997) 'Failure in ZTGSJA. INFO =', info
End If

99999 Format (1X,I5)
99998 Format (3X,8(1P,E12.4))
99997 Format (1X,A,I4)
End Program f08ysfe
```