The right use method of sqrt

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!

Sorry x ** y is not yet supported. Please use ti.sqrt(x) for now.

archibate just now implemented x ** y. This will be released in v0.5.1.