anchor.diff:  *           The initial SIGMA was to the outer end of the spectrum
   *           the matrix is definite and we need not retreat.
               TAU = SPDIAM*EPS*N + TWO*PIVMIN
  +            TAU = MAX( TAU,TWO*EPS*ABS(SIGMA) )
            ELSE
               IF(MB.GT.1) THEN
                  CLWDTH = W(WEND) + WERR(WEND) - W(WBEGIN) - WERR(WBEGIN)
  
positive.code:                ISEED( I ) = 1
   122        CONTINUE
  
              CALL ODRNV(2, ISEED, 2*IN-1, WORK(1))
              DO 125 I = 1,IN-1
                 D(IBEGIN+I-1) = D(IBEGIN+I-1)*(ONE+EPS*PERT*WORK(I))
                 E(IBEGIN+I-1) = E(IBEGIN+I-1)*(ONE+EPS*PERT*WORK(IN+I))
  
negative.code:          IF ( .NOT.USEDQD ) THEN
  *           If ODRRD has been used, shift the eigenvalue approximations
  *           according to their representation. This is necessary for
  *           a uniform DLARRV since dqds computes eigenvalues of the
  *           shifted representation. In DLARRV, W will always hold the
  *           UNshifted eigenvalue approximation.
              DO 134 J=WBEGIN,WEND
                 W(J) = W(J) - SIGMA
  