• Method B -Estimation based on SAS characteristics SAS can provide an excellent estimate of this error if we consider that the linearized model solution is exact. If 𝐾 and ℎ $ are made constant -e.g., at an average temperature along the reactor -, SAS can be used to solve the linear problem. Estimating 𝐾 and ℎ $ at an average temperature, one has approximately the same order of magnitude for the arguments of the exponential functions and for the coefficients of the solution, in comparison with the non-linear problem. For the same number of intervals, the SAS can be programmed to perform approximately the same number of operations both on the linear problem and on the corresponding non-linear problem. For a given 𝜏, the difference between the results of the linear problem, using 𝑘 9CD = 1 and 𝑘 9CD = 𝑁, is due only to the roundoff error. As a result of the previous considerations, it is concluded that an excellent estimate of 𝐸 j;E <=> ( can be obtained from the difference between the results of the SAS for the linear problem with 𝑘 9CD = 1 and with 𝑘 9CD = 𝑁.