1-AUG-2019 SolveSys - Equation Library and Nonlinear Systems Solver

[Han]

So it appears the HP Prime's built-in Solve app has the same issue as the HP48's multiple equation solver (MES): they do not properly analyze inconsistent systems, and return "zeros" that are actually not solutions to the system. Here's an example for the HP48:

http://www.hpmuseum.org/forum/thread-776...l#pid69187

The same problem occurs on the HP Prime. Ask it to solve X+Y=5 and X+Y=6. Set Y to 3 and solve for X to get a "zero" of X=2 and Y=3. I think the problem could be easily fixed by having the Solve app actually check to see if it is indeed a zero of the system, and not just one of the equations. My plan was to include a the Solve app's solver engine as option (among three: quasi-Newton engine in SolveSys, Solve app solver, and a hybrid of the two). It's hard to include it as an option when it fails to check if the system is inconsistent.