Program f07jdfe ! F07JDF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: dpttrf, 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 :: d(:), e(:) ! .. Executable Statements .. Write (nout,*) 'F07JDF Example Program Results' Write (nout,*) ! Skip heading in data file Read (nin,*) Read (nin,*) n Allocate (d(n),e(n-1)) ! Read the lower bidiagonal part of the tridiagonal matrix A from ! data file Read (nin,*) d(1:n) Read (nin,*) e(1:n-1) ! Factorize the tridiagonal matrix A ! The NAG name equivalent of dpttrf is f07jdf Call dpttrf(n,d,e,info) If (info>0) Then Write (nout,99999) 'The leading minor of order ', info, & ' is not positive definite' End If ! Print details of the factorization Write (nout,*) 'Details of factorization' Write (nout,*) Write (nout,*) ' The diagonal elements of D' Write (nout,99998) d(1:n) Write (nout,*) Write (nout,*) ' Sub-diagonal elements of the Cholesky factor L' Write (nout,99998) e(1:n-1) 99999 Format (1X,A,I3,A) 99998 Format (1X,8F9.4) End Program f07jdfe