The nice thing about digital computers, is that they always give us the same results to the same calculations with the same inputs.? There is no possibility of having a different answer, unless either the inputs differ, or an intentional random difference was added to the calculation.? One LSB difference doesn't just happen on its own.
There can be an LSB of uncertainty between an analog quantity and its digital representation.? Or between an exact calculation (with infinite resolution) and a calculation with limited resolution.? But when I ask you to add integers 4 + 6, you'd better always get an answer of 10, and not 9 or 11 (= 10 +/- 1).
FYI, when LTspice needs to back up, it backs up to the previously saved good point.? Then it makes the timestep smaller.? With SPICE2, it made the timestep 1/8 what it was, but LTspice seems to use a different scaling.? Regardless of what that scale number is, there is no reason for it to be 1/8 sometimes, 1/7.9999999999999 sometimes, and 1/8.0000000000001 sometimes (starting from the same point), unless LTspice intentionally gives it that randomness.? It won't just happen because of round-off errors.? It'll be the same every time, because that's how math works on a digital computer.? Same inputs through same calculations --> same results, down to the very last bit.? Even rounding off a calculation is the same every time.
Andy
