Re: problems with N[]
- To: mathgroup at smc.vnet.net
- Subject: [mg38708] Re: problems with N[]
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Mon, 6 Jan 2003 03:42:59 -0500 (EST)
- References: <av94u6$sb9$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
With n <= $MachinePrecision (=16 on my machine) N[n,p] will give a machine number N[Pi,4] 3.14159 Precision[%] 16 Using SetPrecision we can specify precision 4 SetPrecision[Pi,4] 3.142 Precision[%] 4 However, NumberForm (which may be looked up in the Help Browser) allows us to control the display in detail: NumberForm[N[Pi],4] 3.142 Even though we have Precision[%] 16 -- Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565 "1.156" <rob at piovere.com> wrote in message news:av94u6$sb9$1 at smc.vnet.net... > I'm getting a numerical output which has about 12 significant digits. I wanted to give a printout to someone and I need only 4 significant digits (otherwise it represents a result to precise). > > I thought that was what N[] was for so I put out N[result,4]. > > For some reason I still get 12 digits displayed. I looked through he help material and it says > "n must lie between $MinPrecision and $MaxPrecision. $MaxPrecision can be set to Infinity. " > I checked and these numbers are 0 and 10^6, respectively. > > So, I gave up on N[] and tried Ceiling[10000*result]/10000 and damn if I didn't get "6/625" > for an answer. > > I want to display a decimal result with 4 significant digits, can anyone tell me how to do it? > > Thanks. >