function loiarcsin(n,p)
z=zeros(1,p)
for i=1:p
	x=cumsum(2*(rand(1,n)<.5)-1)
	a=bool2s(x(1:(p-1))>0);
	b=bool2s(x(2:p)>0);
	aux=bool2s(a+b>=1);
	z(i)=mean(aux);
end
plot2d(-gsort(-z),[1:p]/p,2)
x=[0:.01:1]
plot2d(x,2*asin(sqrt(x))/%pi,5)
xtitle('Loi de l´arcsinus')