Program f07jnfe ! F07JNF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: nag_wp, zptsv ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Integer :: info, n ! .. Local Arrays .. Complex (Kind=nag_wp), Allocatable :: b(:), e(:) Real (Kind=nag_wp), Allocatable :: d(:) ! .. Executable Statements .. Write (nout,*) 'F07JNF Example Program Results' Write (nout,*) ! Skip heading in data file Read (nin,*) Read (nin,*) n Allocate (b(n),e(n-1),d(n)) ! Read the lower bidiagonal part of the tridiagonal matrix A and ! the right hand side b from data file Read (nin,*) d(1:n) Read (nin,*) e(1:n-1) Read (nin,*) b(1:n) ! Solve the equations Ax = b for x ! The NAG name equivalent of zptsv is f07jnf Call zptsv(n,1,d,e,b,n,info) If (info==0) Then ! Print solution Write (nout,*) 'Solution' Write (nout,99999) b(1:n) ! Print details of factorization Write (nout,*) Write (nout,*) 'Diagonal elements of the diagonal matrix D' Write (nout,99998) d(1:n) Write (nout,*) Write (nout,*) 'Sub-diagonal elements of the Cholesky factor L' Write (nout,99999) e(1:n-1) Else Write (nout,99997) 'The leading minor of order ', info, & ' is not positive definite' End If 99999 Format (4(' (',F8.4,',',F8.4,')':)) 99998 Format ((2X,F7.4,3(11X,F7.4))) 99997 Format (1X,A,I3,A) End Program f07jnfe