Decimal problem using solve

[vterez]

(08-27-2018 04:55 AM)Tim Wessman Wrote:  The quickest way to deal with this is when you get back your empty set [ ]:

(assuming you are in the cas screen)

1. Tap ONCE on your solve(...) entry to select it. (the line about your [ ] empty set)
2. Press the [a b/c] key
3. You get back exact(solve(....)) and it returns an expression as the "answer" containing solve(<all_decimals_converted_to_fractions>)
4. Tap your expression twice and press ENTER. You may need to press shift-Enter for "Approximate" since you'll get back an exact, very big fraction




The [a b/c] key will insert a call to "exact()" which will convert your decimals to fractions which now gives you exact numbers for the calculation. This allows exact, CAS type calculations vs numerical solvers which are inexact by nature and can be thrown easily for a loop if they start with initial bad guesses, or have other types of issues. The reason why you might be seeing different results happening is due to initial guesses. In some cases (from memory, I might be wrong here), the CAS will use random number generation within ranges to seed those guesses. Hence why you might see differing results sometimes.

It worked. Thanks.