Re: Why Mathematica does not issue a warning when the calculations are losing so much precision that the results are not anymore useful?
- To: mathgroup at smc.vnet.net
- Subject: [mg117561] Re: Why Mathematica does not issue a warning when the calculations are losing so much precision that the results are not anymore useful?
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Tue, 22 Mar 2011 05:11:06 -0500 (EST)
Just specify the precision
Table[
N[FractionalPart[(6 + Sqrt[2])^20], n],
{n, 1, 20}] // Column
Table[
N[FractionalPart[(6 + Sqrt[2])^20], n] // InputForm,
{n, 1, 20}] // Column
Bob Hanlon
---- John Travolta Sardus <pireddag at hotmail.com> wrote:
=============
With Mathematica 8.0.1
N[FractionalPart[(6 + Sqrt[2])^20]]
Result:
-160.
Is it a problem for all numerical software being able to recognize when
these calculations cannot be performed with the given machine accuracy?
Does this happen in this case only (where a wrong result is easily
recognized) or in other cases too?
Thanks for any answer,
Giovanni