anchor.diff:        (loop for ind from 0 to (1- (length theta)) do
              (setf (elt theta ind)
                    (- (elt theta ind) (* alpha (elt pd ind)))))
  -      (print theta))))
  +                                        ;(print theta)
  +      )))
   
   ;;; exercise below
   
  
positive.code:         (rowNum (1- (elt (array-dimensions X) 0))))
      (setf result
            (loop for c from 0 to colNum collect
                  (loop for r from 0 to rowNum for temp = (array-slice X r) sum
                       (* (- (logistic-regression (array-multiply temp theta)) (elt y r))
                          (elt temp c)))))
      result))
  
  (defun gradient-descent-lr (X theta y alpha iterTime)
  
negative.code:     (setf result
            (loop for r from 0 to rowNum for temp = (array-slice X r) sum
                 (if (= (nth r y) 1)
                     (- (log (logistic-regression (array-multiply temp theta))))
                     (- (log (- 1 (logistic-regression (array-multiply temp theta))))))))
      (/ result rowNum)))
  
  (defun partial-derivative-lr (X theta y)
  