Plus42 Equations, Preview Release

[Thomas Okken]

I'm not sure what the HP solver is doing there, but it sound like it considers L() to be invertible for its second argument, which would make the equation without the +A*0+B*0 a candidate for the direct solver. The direct solver would then fail, of course, because isolating A or B would lead to a division by zero.

The Plus42 solver does not consider L() to be invertible, so the appearance of the variable to be solved for as the second argument of L() immediately triggers the numerical solver. Also, with the Plus42 solver, a division by zero in the direct solver is not a fatal error, it simply falls back on the numerical solver in that case.

Should the Plus42 solver consider L() to be invertible? I had it that way initially, but changed it to non-invertible, I think because of questions about the evaluation order. If I had a test case for the HP solver, that uses L() with the variable to be solved for as its second argument, and works with the direct solver, and does something useful, I could revisit this issue...