problem with CHS

[Albert Chan]

On XCas, rand(n, 1, 10) does not really meant n random numbers, ranged 1 to 10

I think it meant n random samples from list 1 to 10, thus all elements are unique.
If I try rand(10, 1, 2), XCas session is *crashed*

The random sign sx, sy list may be shortened as 1 liner:

[sx, sy] := makemat(x -> rand(2)*2 - 1, 2, n);