《Programming Abstractions In C》学习第59天，p176-p178总结。

一、技术总结

1.addtive sequences

t_n = t_n-1 + t_n-2

序列：3, 7, 10, 17, 27, 44, 71, 115, 186, 301, 487, 788, 1275, ...

p177, As a general class, the sequences that follow this pattern are called additive sequences。

2.wrapper functions

int Fib(int n) {
    return AdditiveSequence(n, 0, 1);
}

Functions of this sort, which simply return the result of another function, often after transforming the arguments in some way, are called wrapper functions。

如上， Fib称为wrapper function。wrapper函数的作用是为subsidiary function提供参数。

二、英语总结

1.enormous是什么意思？

答：ex-("out of") + norm("rule, norm") + -ous(substituted for Latin -is**, "having, full of")，即超乎寻常的。adj. “extremely large(巨大的)”之意。

2.given that是什么意思？

答：given that 的意思是“taking that fact into account / in consideration of the fact that”，可以翻译为“已知”。that后面的内容一定是fact，不能是假设的。

示例：p176，Given that the Fibonacci function can be implemented efficiently using iteration，the enormous explosion of steps required by the recursive implementation is more that a little disturbing

3.subsidiary是什么意思？

答：

(1)subsidiary: adj.used to refere to sth that less important than sth else with which is connected(辅助的，次要的)。c. a company that is controlled by another(子公司)。

(2)subsidy: c.money given as part of the cost of sth, to help or encourage it to happen(补贴，补助金)。

(3)subside: sub("under") + sidere("to settle")，原本的意思是“sink to the bottom(下沉)”，引申义意义是“sink to a lower level(降低、减弱)”。vi.become less strong or extreme。

三、参考资料

1. 编程

(1)Eric S.Roberts，《Programming Abstractions in C》：https://book.douban.com/subject/2003414

2. 英语

(1)Etymology Dictionary：https://www.etymonline.com

(2) Cambridage Dictionary：https://dictionary.cambridge.org

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