anchor.diff:              ;;
               ;; however
               ;; (float-shift-digits 1.201d0)
  -            ;; => -3, 1201
  +            ;; => 1201, -3
               (multiple-value-bind (scaled-magnitude r)
                   ;; truncate so as to ensure an integral value is passed
                   (truncate (* d (expt 10 n)))
  
positive.code: This funcdtion implements a calculation similar to a base-10
  calculation of the significand and exponent of `d`."
    (declare (type (or integer float) d)
             (values fixnum integer))
    (let ((b d)
          (n 1))
      (declare (type (or integer float) b)
  
negative.code:   => T
  "
    (declare (type integer d)
             (values integer fixnum))
    (cond
      ((zerop d)
       (values 0 0))
  