Program f08yhfe

!     F08YHF Example Program Text

!     Mark 26 Release. NAG Copyright 2016.

!     .. Use Statements ..
Use nag_library, Only: dtgsyl, nag_wp, x04caf
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
Real (Kind=nag_wp)               :: dif, scale
Integer                          :: i, ifail, ijob, info, lda, ldb, ldc, &
ldd, lde, ldf, lwork, m, n
!     .. Local Arrays ..
Real (Kind=nag_wp), Allocatable  :: a(:,:), b(:,:), c(:,:), d(:,:),      &
e(:,:), f(:,:), work(:)
Integer, Allocatable             :: iwork(:)
!     .. Executable Statements ..
Write (nout,*) 'F08YHF Example Program Results'
Write (nout,*)
Flush (nout)
!     Skip heading in data file
lda = m
ldb = n
ldc = m
ldd = m
lde = n
ldf = m
lwork = 1
Allocate (a(lda,m),b(ldb,n),c(ldc,n),d(ldd,m),e(lde,n),f(ldf,n),         &
work(lwork),iwork(m+n+6))

!     Read A, B, D, E, C and F from data file

!     Solve the Sylvester equations
!         A*R - L*B = scale*C and D*R - L*E = scale*F
!     for R and L.
ijob = 0

!     The NAG name equivalent of dtgsyl is f08yhf
Call dtgsyl('No transpose',ijob,m,n,a,lda,b,ldb,c,ldc,d,ldd,e,lde,f,ldf, &
scale,dif,work,lwork,iwork,info)

If (info>=1) Then
Write (nout,99999)
Write (nout,*)
Flush (nout)
End If

!     Print the solution matrices R and L

!     ifail: behaviour on error exit
!             =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
Call x04caf('General',' ',m,n,c,ldc,'Solution matrix R',ifail)

Write (nout,*)
Flush (nout)

ifail = 0
Call x04caf('General',' ',m,n,f,ldf,'Solution matrix L',ifail)

Write (nout,*)
Write (nout,99998) 'SCALE = ', scale

99999 Format (/,' (A,D) and (B,E) have common or very close eigenval','ues.',  &
/,' Perturbed values were used to solve the equations')
99998 Format (1X,A,1P,E10.2)
End Program f08yhfe