A simple matlab function for computing the coefficients of a Lagrange fractional-delay FIR filter is as follows:
function h = lagrange( N, delay )
n = 0:N;
h = ones(1,N+1);
for k = 0:N
index = find(n ~= k);
h(index) = h(index) * (delay-k)./ (n(index)-k);
end