Median

med x    med[x]

Where x is a numeric list returns its median.

q)med 10 34 23 123 5 56
28.5
q)select med price by sym from trade where date=2001.10.10,sym in`AAPL`LEH

med is an aggregate function, equivalent to

{avg x (iasc x)@floor .5*-1 0+count x,:()}