* F07AGF Example Program Text * Mark 15 Release. NAG Copyright 1991. * .. Parameters .. INTEGER NIN, NOUT PARAMETER (NIN=5,NOUT=6) INTEGER NMAX, LDA PARAMETER (NMAX=8,LDA=NMAX) CHARACTER NORM PARAMETER (NORM='1') * .. Local Scalars .. DOUBLE PRECISION ANORM, RCOND INTEGER I, INFO, J, N * .. Local Arrays .. DOUBLE PRECISION A(LDA,NMAX), WORK(4*NMAX) INTEGER IPIV(NMAX), IWORK(NMAX) * .. External Functions .. DOUBLE PRECISION F06RAF, X02AJF EXTERNAL F06RAF, X02AJF * .. External Subroutines .. EXTERNAL DGECON, DGETRF * .. Executable Statements .. WRITE (NOUT,*) 'F07AGF 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,*) ((A(I,J),J=1,N),I=1,N) * * Compute norm of A * ANORM = F06RAF(NORM,N,N,A,LDA,WORK) * * Factorize A * CALL DGETRF(N,N,A,LDA,IPIV,INFO) * WRITE (NOUT,*) IF (INFO.EQ.0) THEN * * Estimate condition number * CALL DGECON(NORM,N,A,LDA,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 U is singular' END IF END IF * 99999 FORMAT (1X,A,1P,E10.2) END