[Gretl-users] Off-topic: cubes of primes

Ok, this is so offtopic that is nearly embarassing, but here goes. I found on the net the attached picture (quite amazing in itself), so I thought it'd be nice to write a hansl script to reproduce it. It turns out the the little script below showcases quite a few features hansl has (eg recursion, logical operators etc), so it could maybe be useful to people who are teaching/learning Hansl. Enjoy! <hansl> set verbose off function matrix prime_sieve(scalar n) x = floor(sqrt(n)) c = seq(2,n) prime = ones(1,n-1) loop i = 2 .. x --quiet prime[i+1:] = prime[i+1:] && !(c[i+1:] % i .= 0) endloop return selifc(c, prime) end function function scalar droot(scalar x) y = floor(x) ret = 0 loop while y >= 1 --quiet ret += y % 10 y = floor(y/10) endloop if ret > 9 ret = droot(ret) endif return ret end function x = prime_sieve(200) loop i = 1 .. nelem(x) --quiet c = x[i]^3 printf "%5d: %5d\n", x[i], droot(c) endloop </hansl> ------------------------------------------------------- Riccardo (Jack) Lucchetti Dipartimento di Scienze Economiche e Sociali (DiSES) Università Politecnica delle Marche (formerly known as Università di Ancona) r.lucchetti(a)univpm.it http://www2.econ.univpm.it/servizi/hpp/lucchetti -------------------------------------------------------