Re: About N in Mathematica 4

*To*: mathgroup at smc.vnet.net*Subject*: [mg25358] Re: About N in Mathematica 4*From*: "Allan Hayes" <hay at haystack.demon.co.uk>*Date*: Sun, 24 Sep 2000 03:01:28 -0400 (EDT)*References*: <8qhn06$j09@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

N[Pi, 3] 3.14159 In fact we get 16 digits for machine numbere (inexact with less than 18 significant digits, test with MachineNumberQ) but only 6 are displayed (controled by option PrintPrecision - see option inspector). % // InputForm 3.141592653589793 To show three decimal places we control the display with NumberForm: NumberForm[N[Pi], {Infinity, 3}] "3.142" Arbitrary precision numbers (eg inexact with >17 significant digits) with precision pr display pr, possibly pr+1, significant digits) NumberForm[N[Pi, 30], DigitBlock -> 5] "3.14159,26535,89793,23846,26433,8328" -- 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 "Sistrall" <silvano.stralla at tin.it> wrote in message news:8qhn06$j09 at smc.vnet.net... > Hi! > > I've a question about the function N in Mathematica 4. I haven't found > information about this problem. > > The question is: why if I use N[Pi,30] I'll have a number of 30 decimal > digits, but with N[Pi,10] or N[Pi,3] I'll get a number of 6 digits? > > The right number of digits is given only if I use a precision bigger than > the precision of the machine. But if I want a number of 3 decimal digits? > > Thanks. > > >