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

[Han]

(02-19-2017 02:45 PM)akmon Wrote:  It happened somethig weird. Tried to solve 1D Elastic Collisions, two equations, fixed m1=1, m2=2, v1i=3 and v1f and v2f as variables to solve. But When I press Ok, it returns to the equations page.CMD line shows "Populating equations in Symb view".
But here is the curiosity. I tried several times pressing OK and [NUM], about 8 times, and guess what, it found a zero!!. And the rest of the times, I change the initial guesses and it solves it flawlessly.

EDit: same behaviour in other systems of equation library. But this time I cannot solve it, always return to equation menu, no matter what guess I input in the vars pending of solving.

What could has happened?

EDIT: Regarding the bold within the quote -- please let me know which system had thes symptoms.

You found a bug in the library file. The system was defined with the variable v2i which does not exist in the system. If you want, you can edit the original file to remove the v2i reference. It should look like:

Code:

{
  "1D Elastic Collisions",
  {
    "v1f=(m1-m2)/(m1+m2)*v1i",
    "v2f=(2*m1)/(m1+m2)*v1i"
  },
  { 1,1 },
  {
    "v1f", "v1i", "v2f", "m1", "m2"
  },
  {
    "Object 1 final velocity",
    "Object 1 initial velocity",
    "Object 2 final velocity",
    "Object 1 mass",
    "Object 2 mass"
  },
  { 0,0,0,0,0 },
  { 0,0,0,0,0 },
  "Forces and Energy"
}

Basically, delete the v2i variable in the fourth list, its description in the fifth list, and remove one of the 0's in both the sixth and seventh lists. You may need to use the utilities I posted earlier to convert the library into a Note file for ease of editing.

EDIT: There is probably another bug in the sweep routine; but the fact that you eventually could solve it suggest that the auto-deletion algorithm is working for abandoned variables.