Program f04bdfe ! F04BDF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: f04bdf, nag_wp, x04caf ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Real (Kind=nag_wp) :: errbnd, rcond Integer :: i, ierr, ifail, lda, ldb, n, nrhs ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: a(:,:), b(:,:) ! .. Executable Statements .. Write (nout,*) 'F04BDF Example Program Results' Write (nout,*) Flush (nout) ! Skip heading in data file Read (nin,*) Read (nin,*) n, nrhs lda = n ldb = n Allocate (a(lda,n),b(ldb,nrhs)) ! Read the upper triangular part of A from data file Read (nin,*)(a(i,i:n),i=1,n) ! Read B from data file Read (nin,*)(b(i,1:nrhs),i=1,n) ! Solve the equations AX = B for X ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 1 Call f04bdf('Upper',n,nrhs,a,lda,b,ldb,rcond,errbnd,ifail) If (ifail==0) Then ! Print solution, estimate of condition number and approximate ! error bound ierr = 0 Call x04caf('General',' ',n,nrhs,b,ldb,'Solution',ierr) Write (nout,*) Write (nout,*) 'Estimate of condition number' Write (nout,99999) 1.0E0_nag_wp/rcond Write (nout,*) Write (nout,*) 'Estimate of error bound for computed solutions' Write (nout,99999) errbnd Else If (ifail==n+1) Then ! Matrix A is numerically singular. Print estimate of ! reciprocal of condition number and solution Write (nout,*) Write (nout,*) 'Estimate of reciprocal of condition number' Write (nout,99999) rcond Write (nout,*) Flush (nout) ierr = 0 Call x04caf('General',' ',n,nrhs,b,ldb,'Solution',ierr) Else If (ifail>0 .And. ifail<=n) Then ! The matrix A is not positive definite to working precision Write (nout,99998) 'The leading minor of order ', ifail, & ' is not positive definite' Else Write (nout,99997) ifail End If 99999 Format (6X,1P,E9.1) 99998 Format (1X,A,I3,A) 99997 Format (1X,' ** F04BDF returned with IFAIL = ',I5) End Program f04bdfe