Re: precision of a measurement (documentation related question)
- To: mathgroup at smc.vnet.net
- Subject: [mg61605] Re: precision of a measurement (documentation related question)
- From: Chris Chiasson <chris.chiasson at gmail.com>
- Date: Sun, 23 Oct 2005 05:46:16 -0400 (EDT)
- References: <acbec1a40510221346r2cee06c3led071a9eeb92d58b@mail.gmail.com> <acbec1a40510221456i64c176d7s73cd5110ac614ba1@mail.gmail.com>
- Sender: owner-wri-mathgroup at wolfram.com
To follow up, here is a function that people could use to compactly enter in measurements and their (half) error range to obtain a number in Mathematica that will have the appropriate significance attached to it (no, I haven't really thought of handling complex numbers yet, but I am sure someone smarter than myself could extend it). Sig[x_,dx_]:=SetPrecision[x,-Log[10,Abs[dx/x]]] Following my previous question: Sig[30,0.5] is the answer I was looking for earlier. This Sig function could be combined with the Notation package to make input even more tidy looking. One could also write a Notation to make numbers with significance show error ranges by default... Regards, On 10/22/05, Chris Chiasson <chris.chiasson at gmail.com> wrote: > Thanks to a Mention by Maxim in this thread: > http://groups.google.com/group/comp.soft-sys.math.mathematica/browse_frm/thread/1768e67ba5ac75f3?tvc=1&q=interval+significance > and the documentation for Interval, > I was able to figure out the answer to my question: > FullForm@Interval[SetPrecision[x,-Log[10,dx/x]]]/.{{x\[Rule]30, > dx\[Rule]0.5},{x\[Rule]30,dx\[Rule]1} > > On 10/22/05, Chris Chiasson <chris.chiasson at gmail.com> wrote: > > Hi Mathgroup, > > If I know that a number (say in inches, measured on a ruler that only > > has marks for inches) and its error are: > > 30 + or - 0.5, > > then looking at the help file for Precision, I see that the precision is: > > -Log[10,dx/x] > > In this case, is dx = 0.5 or is it equal to 1.0?? > > I have noticed that in either case, the number of significant > > digits/the precision is less than 2. > > > > Your thoughts? > > -- > > Chris Chiasson > > http://chrischiasson.com/contact/chris_chiasson > > > > > -- > Chris Chiasson > http://chrischiasson.com/contact/chris_chiasson > -- Chris Chiasson http://chrischiasson.com/contact/chris_chiasson