st: Sqaure root

[flanagan@uchicago.edu]

I am a beginning stat major, and I am trying to figure out how to command the 
stata program to take the square root of a data set, after I have already 
infiled some data.

I typed:

gen square = sqrt{diameter}

but it doesnt work 

it says sqrt not found.

does anyone know the command? 

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