Program f07pgfe ! F07PGF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: dlansp => f06rdf, dspcon, dsptrf, nag_wp, x02ajf ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Real (Kind=nag_wp) :: anorm, rcond Integer :: i, info, j, n Character (1) :: uplo ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: ap(:), work(:) Integer, Allocatable :: ipiv(:), iwork(:) ! .. Executable Statements .. Write (nout,*) 'F07PGF Example Program Results' ! Skip heading in data file Read (nin,*) Read (nin,*) n Allocate (ap(n*(n+1)/2),work(2*n),ipiv(n),iwork(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 ! Compute norm of A ! f06rdf is the NAG name equivalent of the LAPACK auxiliary dlansp anorm = dlansp('1-norm',uplo,n,ap,work) ! Factorize A ! The NAG name equivalent of dsptrf is f07pdf Call dsptrf(uplo,n,ap,ipiv,info) Write (nout,*) If (info==0) Then ! Estimate condition number ! The NAG name equivalent of dspcon is f07pgf Call dspcon(uplo,n,ap,ipiv,anorm,rcond,work,iwork,info) If (rcond>=x02ajf()) Then Write (nout,99999) 'Estimate of condition number =', & 1.0_nag_wp/rcond Else Write (nout,*) 'A is singular to working precision' End If Else Write (nout,*) 'The factor D is singular' End If 99999 Format (1X,A,1P,E10.2) End Program f07pgfe