标准差，通常计算了信号的分析，整体的一部分。但是，有时我们想知道这个数量在不断变化的数据流。 MEANSTDF计算预期的平均值，及其标准差。统计问题常用比较量。-Standard deviation, is usually calculated signal analysis, part of the whole. However, sometimes we want to know the number of ever-changing data streams. MEANSTDF calculate the expected average, and standard deviation. Comparison of the amount of commonly used statistics.