indicator function of an event

例句：

1. 1. The indicator function of a signal is the value at which the signal crosses zero.
   信号的指示函数是信号穿过零值的值。
2. 2. In economics, the indicator function is used to measure the impact of an event on the economy.
   在经济学中，指示函数用于衡量事件对经济的影响。
3. 3. The indicator function can be used to predict future trends in a market.
   指示函数可以用来预测市场的未来趋势。