What am I doing wrong??? When you have an equation such as the one displayed in Equation 1 (see attached figure) and want to compute it by hand, you may rewrite it as Equation 2. Setting X and Y to the following values: X = Exp[-(n-1)/beta] Y = Exp[-T/alpha] I got Equation 3. Thereafter, I tried to transform it in the same way, and then I got Equation 4. However, Equation 3 and 4 are not the same. For alpha=360, beta=5, A1=10 and T=1, these two equations give very different curves, as you can see at the bottom of the image (Equation 3 represented as the purple curve, and Equation 4 represented as the blue line). What am I doing wrong? Thanks in advance, Estevão P.S.: Please, I really need help in this issue.