function [x,F]=stabledens(a)
%estimates the standard symmetric stable(a) pdf using simulation from a Poisson distribution
% at x=.01:.01:1
Y=cumsum(poissrnd(.1,100,1000));  % row i of P is Poisson(i/10)
F=(cos(pi*Y).*gamma(.5*(Y+1)).*(-1).^Y);
F=mean(F')/(pi*a);
x=.01:.01:1;

