function A=norm_fac(n,l)
%
% A=norm_fac(n,l)
% calculate normalication factor for the radial wavefunction
%           
%                        R_{n,l}(r)
%
a=1;
Z=1;
% Determines the length in atomic units and the nuclear harge.
A=sqrt((((2*Z)/(n*a))^3*prod(1:(n-l-1)))/(2*n*(prod(1:(n+l))^3)));
