神经网络学习笔记（二）：feedforward和feedback

维基百科解释：

Feed-forward, sometimes written feedforward, is a term describing an element or pathway within a control system that passes a controlling signal from a source in its external environment, often a command signal from an external operator, to a load elsewhere in its external environment. A control system which has only feed-forward behavior responds to its control signal in a pre-defined way without responding to how the load reacts; it is in contrast with a system that also has feedback, which adjusts the output to take account of how it affects the load, and how the load itself may vary unpredictably; the load is considered to belong to the external environment of the system.

理解：Feedforward 与 Feedback的区别在于：使用 feedforward 机制的系统没有反馈（feedback），也就是不会根据输出结果对输入结果的影响来进一步调整输出结果。