% for statement from T Van Le 92
for(I,I,N):-I =< N.
for(I,M,N):-M < N, M1 is M+1, for(I,M1,N).

for(I,N):-for(I,1,N).

% interesting examples of searches - pythagorean triples, 4 square make an integer and so on.
sample(N):-for(I,1,N), for(J,1,I), for(K,1,J),print([I,J,K]).
pyth(N):-for(I,N), I1 is I+1, for(J,I), for(K,I1,N), 
	K*K=:=I*I+J*J, print([J,I,K]).
isqrt(N,Sqrt):-for(I,1,N), I*I>N,!, Sqrt is I-1.
lagrange(N):-isqrt(N,L),
	I1 is N - L*L, for(I,0,I1),
	J1 is I1 - I*I, for(J,I,J1),
	K1 is J1 - J*J, for(K,J,K1),
	N=:=I*I+J*J+K*K+L*L,print,print([I,J,K,L]).