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Restrictions of use

The tool that we use to solve the system is interval analysis that imposes some restrictions, not on the mathematical functions that appear in the expressions but on the way we handle their definition domain.

Assume for example that one of the expressions is: sin(x)+1/(x-1)=0 with as search domain for x: [-10,10].

The interval evaluation of x-1 is then [-11,9], that includes 0. But the interval evaluation of the expression 1/X, where X is an interval is prohibited if the interval includes 0. Hence we will not be able to evaluate this expression and the solver will fail.

We will get the same problem for the following examples:

  • sqrt(X) where X includes negative numbers,
  • arccos, arcsin(X) where X has bounds either smaller than -1 or greater than 1
  • log(X) where the lower bound of X is negative.

There are means to deal with this problem but they are not available in the current solver. However you may still submit your system and if you have provided a valid e-mail we will contact you after having dealt with your problem.