SQRT(expression)
$ nano mathsqrt.txt
$ cat mathsqrt.txt
$ hdfs dfs-put mathsqrt.txt /pigexample
$ pig
grunt> A = LOAD '/pigexample/mathsqrt.txt' AS (a1:float) ;
grunt> DUMP A;
grunt> Result = FOREACH A GENERATE SQRT(a1); grunt> DUMP Result;