Program f08qvfe ! F08QVF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: nag_wp, x04dbf, ztrsyl ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Real (Kind=nag_wp) :: scale Integer :: i, ifail, info, lda, ldb, ldc, m, n ! .. Local Arrays .. Complex (Kind=nag_wp), Allocatable :: a(:,:), b(:,:), c(:,:) Character (1) :: clabs(1), rlabs(1) ! .. Executable Statements .. Write (nout,*) 'F08QVF 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 ! The NAG name equivalent of ztrsyl is f08qvf Call ztrsyl('No transpose','No transpose',1,m,n,a,lda,b,ldb,c,ldc,scale, & info) If (info>=1) Then Write (nout,99999) 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 x04dbf('General',' ',m,n,c,ldc,'Bracketed','F8.4', & 'Solution Matrix','I',rlabs,'I',clabs,80,0,ifail) 99999 Format (/' A and B have common or very close eigenvalues.'/' Pe', & 'rturbed values were used to solve the equations') End Program f08qvfe