Re: Significance Arithmetic
- To: mathgroup at smc.vnet.net
- Subject: [mg37014] Re: Significance Arithmetic
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Sun, 6 Oct 2002 05:33:12 -0400 (EDT)
- References: <000001c26bd9$e486f400$0300a8c0@HolyCow>
- Sender: owner-wri-mathgroup at wolfram.com
Bobby,
One point:
>.... bigfloats ... [are] the result of using N[expr,k] or
SetAccuracy[expr,k] where k is bigger than machine precision. If k <=
> machine > precision, the result is a machine precision number.
We get bigfloats with k<=machine precision with SetAccuracy and
SetPrecision but not with N:
Example
a=SetPrecision[2.3,5]
2.3000
Precision[a]
5.
Precision[a^2000]
1.69897
Also, of course, when more than machine precision significant digits are
given
a=1.01234567891234500;
Precision[a]
17.301
Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
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