anchor.diff:  C   CHECK CONVERGENCE
   
         mode = 0
  -      IF (h1.LT.acc .AND. h2.LT.acc .AND. .NOT. badlin) GO TO 330
  +      IF (h1.LT.acc .AND. h2.LT.acc .AND. .NOT. badlin
  +     *     .AND. f .EQ. f) GO TO 330
         h1 = ZERO
         DO 180 j=1,m
            IF (j.LE.meq) THEN
  
positive.code: 
    255 CONTINUE
        IF ((ABS(f-f0).LT.tol .OR. dnrm2_(n,s,1).LT.tol) .AND. h3.LT.tol
       *     .AND. .NOT. badlin)
       *   THEN
              mode = 0
           ELSE
  
negative.code:          h3 = h3 + MAX(-c(j),h1)
    250 CONTINUE
        IF ((ABS(f-f0).LT.acc .OR. dnrm2_(n,s,1).LT.acc) .AND. h3.LT.acc
       *     .AND. .NOT. badlin .AND. f .EQ. f)
       *   THEN
              mode = 0
           ELSE
  