* F07MGF Example Program Text * Mark 15 Release. NAG Copyright 1991. * .. Parameters .. INTEGER NIN, NOUT PARAMETER (NIN=5,NOUT=6) INTEGER NMAX, LDA, LWORK PARAMETER (NMAX=8,LDA=NMAX,LWORK=64*NMAX) * .. Local Scalars .. DOUBLE PRECISION ANORM, RCOND INTEGER I, INFO, J, N CHARACTER UPLO * .. Local Arrays .. DOUBLE PRECISION A(LDA,NMAX), WORK(LWORK) INTEGER IPIV(NMAX), IWORK(NMAX) * .. External Functions .. DOUBLE PRECISION F06RCF, X02AJF EXTERNAL F06RCF, X02AJF * .. External Subroutines .. EXTERNAL DSYCON, DSYTRF * .. Executable Statements .. WRITE (NOUT,*) 'F07MGF 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 * * Compute norm of A * ANORM = F06RCF('1-norm',UPLO,N,A,LDA,WORK) * * Factorize A * CALL DSYTRF(UPLO,N,A,LDA,IPIV,WORK,LWORK,INFO) * WRITE (NOUT,*) IF (INFO.EQ.0) THEN * * Estimate condition number * CALL DSYCON(UPLO,N,A,LDA,IPIV,ANORM,RCOND,WORK,IWORK,INFO) * IF (RCOND.GE.X02AJF()) THEN WRITE (NOUT,99999) 'Estimate of condition number =', + 1.0D0/RCOND ELSE WRITE (NOUT,*) 'A is singular to working precision' END IF ELSE WRITE (NOUT,*) 'The factor D is singular' END IF END IF STOP * 99999 FORMAT (1X,A,1P,D10.2) END