* F07HGF Example Program Text * Mark 15 Release. NAG Copyright 1991. * .. Parameters .. INTEGER NIN, NOUT PARAMETER (NIN=5,NOUT=6) INTEGER NMAX, KDMAX, LDAB PARAMETER (NMAX=8,KDMAX=8,LDAB=KDMAX+1) * .. Local Scalars .. DOUBLE PRECISION ANORM, RCOND INTEGER I, INFO, J, KD, N CHARACTER UPLO * .. Local Arrays .. DOUBLE PRECISION AB(LDAB,NMAX), WORK(3*NMAX) INTEGER IWORK(NMAX) * .. External Functions .. DOUBLE PRECISION F06REF, X02AJF EXTERNAL F06REF, X02AJF * .. External Subroutines .. EXTERNAL DPBCON, DPBTRF * .. Intrinsic Functions .. INTRINSIC MAX, MIN * .. Executable Statements .. WRITE (NOUT,*) 'F07HGF Example Program Results' * Skip heading in data file READ (NIN,*) READ (NIN,*) N, KD IF (N.LE.NMAX .AND. KD.LE.KDMAX) THEN * * Read A from data file * READ (NIN,*) UPLO IF (UPLO.EQ.'U') THEN DO 20 I = 1, N READ (NIN,*) (AB(KD+1+I-J,J),J=I,MIN(N,I+KD)) 20 CONTINUE ELSE IF (UPLO.EQ.'L') THEN DO 40 I = 1, N READ (NIN,*) (AB(1+I-J,J),J=MAX(1,I-KD),I) 40 CONTINUE END IF * * Compute norm of A * ANORM = F06REF('1-norm',UPLO,N,KD,AB,LDAB,WORK) * * Factorize A * CALL DPBTRF(UPLO,N,KD,AB,LDAB,INFO) * WRITE (NOUT,*) IF (INFO.EQ.0) THEN * * Estimate condition number * CALL DPBCON(UPLO,N,KD,AB,LDAB,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,*) 'A is not positive-definite' END IF END IF STOP * 99999 FORMAT (1X,A,1P,E10.2) END