Program ztrsyl_example
! ZTRSYL Example Program Text
! Copyright 2017, Numerical Algorithms Group Ltd. http://www.nag.com
! .. Use Statements ..
Use lapack_example_aux, Only: nagf_file_print_matrix_complex_gen_comp
Use lapack_interfaces, Only: ztrsyl
Use lapack_precision, Only: dp
! .. Implicit None Statement ..
Implicit None
! .. Parameters ..
Integer, Parameter :: nin = 5, nout = 6
! .. Local Scalars ..
Real (Kind=dp) :: scale
Integer :: i, ifail, info, lda, ldb, ldc, m, n
! .. Local Arrays ..
Complex (Kind=dp), Allocatable :: a(:, :), b(:, :), c(:, :)
Character (1) :: clabs(1), rlabs(1)
! .. Executable Statements ..
Write (nout, *) 'ZTRSYL Example Program Results'
Write (nout, *)
Flush (nout)
! Skip heading in data file
Read (nin, *)
Read (nin, *) m, n
lda = m
ldb = n
ldc = m
Allocate (a(lda,m), b(ldb,n), c(ldc,n))
! Read A, B and C from data file
Read (nin, *)(a(i,1:m), i=1, m)
Read (nin, *)(b(i,1:n), i=1, n)
Read (nin, *)(c(i,1:n), i=1, m)
! Solve the Sylvester equation A*X + X*B = C for X
Call ztrsyl('No transpose', 'No transpose', 1, m, n, a, lda, b, ldb, c, &
ldc, scale, info)
If (info>=1) Then
Write (nout, 100)
Write (nout, *)
Flush (nout)
End If
! Print X
! ifail: behaviour on error exit
! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
Call nagf_file_print_matrix_complex_gen_comp('General', ' ', m, n, c, &
ldc, 'Bracketed', 'F8.4', 'Solution Matrix', 'I', rlabs, 'I', clabs, &
80, 0, ifail)
100 Format (/, ' A and B have common or very close eigenvalues.', /, ' Pe', &
'rturbed values were used to solve the equations')
End Program