记忆化

sympy.utilities.memoization.assoc_recurrence_memo(base_seq)

从基础开始的递归定义的关联序列的备忘录装饰器

base_seq(n) – 可调用对象以获取基本序列元素

XXX 仅适用于 Pn0 = base_seq(0) 的情况 XXX 仅适用于 m <= n 的情况

sympy.utilities.memoization.recurrence_memo(initial)

用于由递归定义的序列的备忘录装饰器

示例

>>> from sympy.utilities.memoization import recurrence_memo
>>> @recurrence_memo([1]) # 0! = 1
... def factorial(n, prev):
...     return n * prev[-1]
>>> factorial(4)
24
>>> factorial(3) # use cache values
6
>>> factorial.cache_length() # cache length can be obtained
5
>>> factorial.fetch_item(slice(2, 4))
[2, 6]