eq (hz-&gt;radians (* frm-int frq)))
             (setf even-freq (hz-&gt;radians (* (+ frm-int 1) frq)))
             (setf even-amp (- frm0 frm-int))
             (setf odd-amp (- 1.0 even-amp))))
         (incf sum (+ (* (aref amps k) 
                      (+ (* even-amp 
                            (oscil (aref evens k) 
                              (+ even-freq (* (aref indices k) car))))
                         (* odd-amp 
                             (oscil (aref odds k) 
                         