1. NL is not a Spice! (cont.)

1.3. What does NL5 do? I can imagine only 3 reasons why Spice could not simulate a schematic:
1) Schematic topology is absolutely wrong;
2) Schematic is correct, but component parameters are wrong;
3) Everything is correct, but Spice can not simulate...

NL can't do anything with #3: it is Spice responsibility to do things right. As for #1 and #2: a responsible party here is an engineer, who invents schematic, selects parts, and must guarantee workable solution for further Spice simulation. NL can help engineer to do this job quick and efficient.

How does engineer create a new schematic? Mostly in his head. Or on the sheet of paper with pencil and eraser. Or on the blackboard. In any case, all the calculations and evaluations are done in his brain in the form: "this diode is close, current goes here, capacitor is charged, switch opens...". Just note: no real parts here, only "diode", "switch", "OpAmp". Advantage of using NL on this stage of the project is that it is designed to do reliable simulation of schematics with ideal components: "diodes", "switches", "OpAmps", etc., and most of the time it does it well. Spice simulators can't do that reliably just because their algorithm is not designed for ideal components. Although some simulators claim that they can, very often they are failing at very simple schematics.