Program f07cafe ! F07CAF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: dgtsv, nag_wp ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Integer :: info, n ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: b(:), d(:), dl(:), du(:) ! .. Executable Statements .. Write (nout,*) 'F07CAF Example Program Results' Write (nout,*) ! Skip heading in data file Read (nin,*) Read (nin,*) n Allocate (b(n),d(n),dl(n-1),du(n-1)) ! Read the tridiagonal matrix A and the right hand side B from ! data file Read (nin,*) du(1:n-1) Read (nin,*) d(1:n) Read (nin,*) dl(1:n-1) Read (nin,*) b(1:n) ! Solve the equations Ax = b for x ! The NAG name equivalent of dgtsv is f07caf Call dgtsv(n,1,dl,d,du,b,n,info) If (info==0) Then ! Print solution Write (nout,*) 'Solution' Write (nout,99999) b(1:n) Else Write (nout,99998) 'The (', info, ',', info, ')', & ' element of the factor U is zero' End If 99999 Format ((1X,7F11.4)) 99998 Format (1X,A,I3,A,I3,A,A) End Program f07cafe