Program f07tvfe ! F07TVF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: nag_wp, x04dbf, ztrrfs, ztrtrs ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 Character (1), Parameter :: diag = 'N', trans = 'N' ! .. Local Scalars .. Integer :: i, ifail, info, lda, ldb, ldx, n, nrhs Character (1) :: uplo ! .. Local Arrays .. Complex (Kind=nag_wp), Allocatable :: a(:,:), b(:,:), work(:), x(:,:) Real (Kind=nag_wp), Allocatable :: berr(:), ferr(:), rwork(:) Character (1) :: clabs(1), rlabs(1) ! .. Executable Statements .. Write (nout,*) 'F07TVF Example Program Results' ! Skip heading in data file Read (nin,*) Read (nin,*) n, nrhs lda = n ldb = n ldx = n Allocate (a(lda,n),b(ldb,nrhs),work(2*n),x(ldx,n),berr(nrhs),ferr(nrhs), & rwork(n)) ! Read A and B from data file, and copy B to X Read (nin,*) uplo If (uplo=='U') Then Read (nin,*)(a(i,i:n),i=1,n) Else If (uplo=='L') Then Read (nin,*)(a(i,1:i),i=1,n) End If Read (nin,*)(b(i,1:nrhs),i=1,n) x(1:n,1:nrhs) = b(1:n,1:nrhs) ! Compute solution in the array X ! The NAG name equivalent of ztrtrs is f07tsf Call ztrtrs(uplo,trans,diag,n,nrhs,a,lda,x,ldx,info) ! Compute backward errors and estimated bounds on the ! forward errors ! The NAG name equivalent of ztrrfs is f07tvf Call ztrrfs(uplo,trans,diag,n,nrhs,a,lda,b,ldb,x,ldx,ferr,berr,work, & rwork,info) ! Print solution Write (nout,*) Flush (nout) ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 Call x04dbf('General',' ',n,nrhs,x,ldx,'Bracketed','F7.4','Solution(s)', & 'Integer',rlabs,'Integer',clabs,80,0,ifail) Write (nout,*) Write (nout,*) 'Backward errors (machine-dependent)' Write (nout,99999) berr(1:nrhs) Write (nout,*) 'Estimated forward error bounds (machine-dependent)' Write (nout,99999) ferr(1:nrhs) 99999 Format ((5X,1P,4(E11.1,7X))) End Program f07tvfe