Re: HP35S solve problem Message #2 Posted by Dieter on 31 Dec 2011, 10:51 a.m., in response to message #1 by Alessandro Castellani (Italy)
Alessandro, there's nothing wrong with your 35s. You just discovered a feature that is often overlooked: the 35s can solve equations symbolically. It does so if the variable appears only once in the equation.
This also happens in your case. Here, the equation
X^2  4
or
X^2  4 = 0
is automatically transformed to
X = SQRT(4)
This exact solution is then evaluated by the 35s, using its regular functions. So the square root always returns a positive result.
This also means that  in such a case  the two initial guesses do not matter at all, they are completely ignored.
If you want the usual numerical solution by successive iteration, simply change the equation a bit so that the variable appears twice:
X*X  4
or
X^2  4 = 0*X
All this has been discussed before. For more information and further details, please take a look at this thread.
Dieter
Edited: 31 Dec 2011, 11:18 a.m.
