Matlab code for the equation

I had written partial code for this equation but i want to confirm whether its written correct or not. My code is

for r = 1:1:length(R)% summ2

sum2 = 0;

prod=1;

for k= 1:1:length(R) % prod

if k~=r %when k not equal r

v1 = (1/lam(k))/ ((1/lam(k))-(1/lam(r)));

prod=prod*v1;

end

end

end