类似于数学中，有个f(x),然后求指定a—b时f(x)的值 f(x)可以自定义
上代码
package com.ysk /** * Created by Y.S.K on 2017/8/31 in spark02. * 求a---b f(x) */ object sumfunc extends App { def sum(f: Int => Int)(a: Int)(b: Int): Int = { @annotation.tailrec def loop(n: Int, acc: Int): Int = { if (n > b) { println(s"n=${n},acc=${acc}") acc } else { println(s"n=${n},acc=${acc}") loop(n + 1, acc + f(n)) } } loop(a, 0) } sum(x => x)(1)(5) sum(x => x * x)(1)(5) sum(x => x * x * x)(1)(5) val sumSquare = sum(x => x * x * x) _ sumSquare(1)(5) }输出结果
n=1,acc=0 n=2,acc=1 n=3,acc=3 n=4,acc=6 n=5,acc=10 n=6,acc=15 n=1,acc=0 n=2,acc=1 n=3,acc=5 n=4,acc=14 n=5,acc=30 n=6,acc=55 n=1,acc=0 n=2,acc=1 n=3,acc=9 n=4,acc=36 n=5,acc=100 n=6,acc=225 n=1,acc=0 n=2,acc=1 n=3,acc=9 n=4,acc=36 n=5,acc=100 n=6,acc=225
