hello yuanming:

i found it really hard to calculate sqrt value of a number in taichi. it can not be get by y=x**0,5, because it will report some error like this:

Python36\site-packages\taichi\lang\expr.py", line 246, in **pow**

assert isinstance(power, int) and power >= 0

can you tell me the right way to calculate sqrt value of a number? Thank you!