Hi,The continuous time forward rate could be written as:f(m,n)= n*s(0,n)-m*s(0,m)/(n-m)where f is the forward rate between time m and n, s(0,n) is the spot rate with maturity n and s(0,m) is the spot rate with maturity m.I am a little bit confused about the formula, if I want to bring a payment back from period m to n should I multiply directly by exponential (-f ) or multiply it by exponential (-f*(m-n))? i mean should i use the m-n twice in computing the forward rate and in the discounting or once (in the forward rate computation or equivalently in the discounting)