Program f07pjfe ! F07PJF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: dsptrf, dsptri, nag_wp, x04ccf ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Integer :: i, ifail, info, j, n Character (1) :: uplo ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: ap(:), work(:) Integer, Allocatable :: ipiv(:) ! .. Executable Statements .. Write (nout,*) 'F07PJF Example Program Results' ! Skip heading in data file Read (nin,*) Read (nin,*) n Allocate (ap(n*(n+1)/2),work(n),ipiv(n)) ! Read A from data file Read (nin,*) uplo If (uplo=='U') Then Read (nin,*)((ap(i+j*(j-1)/2),j=i,n),i=1,n) Else If (uplo=='L') Then Read (nin,*)((ap(i+(2*n-j)*(j-1)/2),j=1,i),i=1,n) End If ! Factorize A ! The NAG name equivalent of dsptrf is f07pdf Call dsptrf(uplo,n,ap,ipiv,info) Write (nout,*) Flush (nout) If (info==0) Then ! Compute inverse of A ! The NAG name equivalent of dsptri is f07pjf Call dsptri(uplo,n,ap,ipiv,work,info) ! Print inverse ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 Call x04ccf(uplo,'Nonunit',n,ap,'Inverse',ifail) Else Write (nout,*) 'The factor D is singular' End If End Program f07pjfe