sqlite studio user defined function

sqlite studio does not support square root function, so i have defined it in function editor as

    proc SqrtA {num} {  set ans [expr {sqrt($num)}] return $ans }

with function name SqrtA and one input argument, lang. tcl but when i am using it in query editor, i am not getting the square root.

for example i had tried for -

    select SqrtA(9);

can anyone please help me, in how to include square root function in sqlite studio?