Re: Precision of calculations

*To*: mathgroup at smc.vnet.net*Subject*: [mg109469] Re: Precision of calculations*From*: DrMajorBob <btreat1 at austin.rr.com>*Date*: Wed, 28 Apr 2010 02:00:41 -0400 (EDT)

If Abs[f'[x]] > 1, then f[x] has LESS precision than x. If x is machine precision, there's no tracking of that loss of precision, so you could end up with no meaningful digits without knowing it. If x is "arbitrary precision", there IS tracking... but it tends to be pessimistic. You might lose precision (according to Mathematica) even though -1 < f'[x] < 1. In that case, you lose precision but shouldn't. Bobby On Tue, 27 Apr 2010 03:04:32 -0500, Jim Lambaugh <lambaugh at gmail.com> wrote: > Hi guys > > When I write numbers in my code, I do it as (e.g.) > > 1.0 > 1000.0 > Pi //N > etc... > > Is it correct to say that my calculations are done with machine- > precision, i.e. with rougly 16 digit precision? > > Regards, > Jim. > -- DrMajorBob at yahoo.com