PROGRAM f07uhfe ! F07UHF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. Use Statements .. USE nag_library, ONLY : dtprfs, dtptrs, nag_wp, x04caf ! .. 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, j, ldb, ldx, n, nrhs CHARACTER (1) :: uplo ! .. Local Arrays .. REAL (KIND=nag_wp), ALLOCATABLE :: ap(:), b(:,:), berr(:), ferr(:), & work(:), x(:,:) INTEGER, ALLOCATABLE :: iwork(:) ! .. Executable Statements .. WRITE (nout,*) 'F07UHF Example Program Results' ! Skip heading in data file READ (nin,*) READ (nin,*) n, nrhs ldb = n ldx = n ALLOCATE (ap(n*(n+1)/2),b(ldb,nrhs),berr(nrhs),ferr(nrhs),work(3*n),x( & ldx,n),iwork(n)) ! Read A and B from data file, and copy B to X 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 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 dtptrs is f07uef CALL dtptrs(uplo,trans,diag,n,nrhs,ap,x,ldx,info) ! Compute backward errors and estimated bounds on the ! forward errors ! The NAG name equivalent of dtprfs is f07uhf CALL dtprfs(uplo,trans,diag,n,nrhs,ap,b,ldb,x,ldx,ferr,berr,work,iwork, & 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 x04caf('General',' ',n,nrhs,x,ldx,'Solution(s)',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 ((3X,1P,7E11.1)) END PROGRAM f07uhfe