* F08FEF Example Program Text * Mark 16 Release. NAG Copyright 1992. * .. Parameters .. INTEGER NIN, NOUT PARAMETER (NIN=5,NOUT=6) INTEGER NMAX, LDA, LWORK PARAMETER (NMAX=8,LDA=NMAX,LWORK=64*NMAX) * .. Local Scalars .. INTEGER I, INFO, J, N CHARACTER UPLO * .. Local Arrays .. DOUBLE PRECISION A(LDA,NMAX), D(NMAX), E(NMAX-1), TAU(NMAX-1), + WORK(LWORK) * .. External Subroutines .. EXTERNAL DSYTRD * .. Executable Statements .. WRITE (NOUT,*) 'F08FEF Example Program Results' * Skip heading in data file READ (NIN,*) READ (NIN,*) N IF (N.LE.NMAX) THEN * * Read A from data file * READ (NIN,*) UPLO IF (UPLO.EQ.'U') THEN READ (NIN,*) ((A(I,J),J=I,N),I=1,N) ELSE IF (UPLO.EQ.'L') THEN READ (NIN,*) ((A(I,J),J=1,I),I=1,N) END IF * * Reduce A to tridiagonal form * CALL DSYTRD(UPLO,N,A,LDA,D,E,TAU,WORK,LWORK,INFO) * * Print tridiagonal form * WRITE (NOUT,*) WRITE (NOUT,*) 'Diagonal' WRITE (NOUT,99999) (D(I),I=1,N) WRITE (NOUT,*) 'Off-diagonal' WRITE (NOUT,99999) (E(I),I=1,N-1) END IF STOP * 99999 FORMAT (1X,8F9.4) END