I found a solution. I defined a new function called
delta = myAngDiff(alpha,beta)
which takes is expected to take a single value for alpha and a vector for beta and use a for loop to iterate through all the difference between alpha and each intry in beta. Here it is:
function out = myAngDiff(alpha,beta)
out = zeros(length(beta),1);
for i=1:length(beta)
out(i) = abs(angdiff(alpha,beta(i)));
end
end