loi=[0.5 0.2 0.1 0.2]';nbsimul=10;nmax=100;
for k=1:nbsimul
z=1;nbgen=0;
while z($)>0&z($)<nmax
z=[z,(0:length(loi)-1)*grand(1,'mul',z($),loi(1:$-1))];
nbgen=nbgen+1;
end;
plot2d(0:nbgen,z,style=k);
end;