Functions for taking the mean and standard deviation of an array of numbers?

I've been thinking about how to help Arduino users do more sophisticated analysis of their sensor data and this seems like a simple thing that could help with a bunch of things. There are some existing libraries for this (e.g. http://playground.arduino.cc/Main/Average) but it seems like mean() and standardDeviation() are common enough to be worth including in the core. What do you think?

未指定文件、测试或入口点。首先查看 ArduinoCore-API 组织和现有的 core API，然后确定适当的数组接口、数值行为以及所需的测试，再决定完整的添加需要包含哪些内容。

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