1 引言 ............................................................................................................................................... 2 1 .1 编写目的 ................................................................................................................................. 2 1 .2 背景......................................................................................................................................... 2 1 .3 定义......................................................................................................................................... 3 1 .4 参考资料 ................................................................................................................................. 3 2 任务概述 ....................................................................................................................................... 4 2 .1 目标......................................................................................................................................... 4 2 .2 用户的特点 ............................................................................................................................. 4 2 .3 假定和约束 ............................................................................................................................. 4 3 需求规定 ....................................................................................................................................... 4 3 .1 对功能的规定 ......................................................................................................................... 4 3 .2 对性能的规定 ......................................................................................................................... 4 3 .2 .1 精度 .................................................................................................................................. 7 3 .2 .2 时间特性要求 .......