PROGRAM f07mjfe ! F07MJF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. Use Statements .. USE nag_library, ONLY : dsytrf, dsytri, nag_wp, x04caf ! .. Implicit None Statement .. IMPLICIT NONE ! .. Parameters .. INTEGER, PARAMETER :: nin = 5, nout = 6 ! .. Local Scalars .. INTEGER :: i, ifail, info, lda, lwork, n CHARACTER (1) :: uplo ! .. Local Arrays .. REAL (KIND=nag_wp), ALLOCATABLE :: a(:,:), work(:) INTEGER, ALLOCATABLE :: ipiv(:) ! .. Executable Statements .. WRITE (nout,*) 'F07MJF Example Program Results' ! Skip heading in data file READ (nin,*) READ (nin,*) n lda = n lwork = 64*n ALLOCATE (a(lda,n),work(lwork),ipiv(n)) ! Read A from data file 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 ! Factorize A ! The NAG name equivalent of dsytrf is f07mdf CALL dsytrf(uplo,n,a,lda,ipiv,work,lwork,info) WRITE (nout,*) FLUSH (nout) IF (info==0) THEN ! Compute inverse of A ! The NAG name equivalent of dsytri is f07mjf CALL dsytri(uplo,n,a,lda,ipiv,work,info) ! Print inverse ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 CALL x04caf(uplo,'Nonunit',n,n,a,lda,'Inverse',ifail) ELSE WRITE (nout,*) 'The factor D is singular' END IF END PROGRAM f07mjfe