I had the same problem. I found a function definition for finitepmf() within this document:
function pmf=finitepmf(sx,px,x)
% finite random variable X:
% vector sx of sample space
% elements {sx(1),sx(2), ...}
% vector px of probabilities
% px(i)=P[X=sx(i)]
% Output is the vector
% pmf: pmf(i)=P[X=x(i)]
pmf=zeros(size(x(:)));
for i=1:length(x)
pmf(i)= sum(px(find(sx==x(i))));
end
end
