2015/11/05

# SICP 問題 2.91

```
(define (div-terms L1 L2)
(if (empty-termlist? L1)
(list (the-empty-termlist) (the-empty-termlist))
(let ((t1 (first-term L1))
(t2 (first-term L2)))
(if (> (order t2) (order t1))
(list (the-empty-termlist) L1)
(let ((new-c (div (coeff t1) (coeff t2)))
(new-o (- (order t1) (order t2))))
(let ((rest-of-result
(div-terms (sub-terms L1
(mul-terms L2
(make-term new-o
new-c)))
L2)))
(list (add-terms (list (make-term new-o new-c))
(car rest-of-result))
(cadr rest-of-result))))))))
(define (div-poly p1 p2)
(if (same-variable? (variable p1) (variable p2))
(make-poly (variable p1)
(div (term-list p1)
(term-list p2)))
(error "Polys not in same var -- DIV POLY"
(list p1 p2))))
```