Jacob Kirbawi writes:
> This is either a bug in the function ER(N) ("square root of N")
> or I might be using the function outside its defined domain :

Frank Celler writes:
> the manual requires that N is a positive integer (see "ATALS
> irrationalities"), but I agree 'ER' should either signal an error or
> give the expected result or the manual should be even more definite in
> restricting the domain.

I started to write a reply just along these lines, but one thing stopped me
short. At the end of 13.12 -- ATLAS irrationalities in the manual, there's
an example which looks like this:

gap> EW(16,3); EW(17,2); ER(3); ER(-3); EY(5); EB(9);
0
E(17)+E(17)^4+E(17)^13+E(17)^16
-E(12)^7+E(12)^11
E(3)-E(3)^2
E(5)+E(5)^4
1

where ER(-3) supposedly returns E(3)-E(3)^2.

Either someone's got a fancy unreleased version of GAP, or they cheated a bit
with the examples ;)

-Lewis (lmccarth@klingon.cs.umass.edu)