PROGRAM f07tvfe ! F07TVF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. 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