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Re: a problem about mathematica output

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82441] Re: a problem about mathematica output
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
  • Date: Sat, 20 Oct 2007 05:54:20 -0400 (EDT)
  • Organization: The Open University, Milton Keynes, UK
  • References: <ff9rli$4nj$1@smc.vnet.net>

qwer wrote:

> I have a puzzle when using mathematica, I want to out put my resuts to
> a .dat file ,but I do not know how to control the digital,  for
> example:
> 
> the mathematica code is
> 
> f[x_]:=NIntegrate[Sin[y]/y,{y,0,x}];
> OpenWrite["xx.dat",FormatType->TextForm];
> Do[Write["xx.dat",N[x,4],"   ",N[f[x],4]],{x,0.001,1,0.05}];
> Close["xx.dat"];
> 
> then in xx.dat you can find
> 0   0.
> 0.05   0.0499931
> 0.1   0.0999445
> 0.15   0.149813
> 0.2   0.199556
> 0.25   0.249134
> .
> .
> but I want it can be written in the form
> 0.000   0.000
> 0.050   0.050
> 0.100   0.100
> 0.150   0.150
> 0.200   0.200
> 0.250   0.249
> .
> .
> It will be look much better!

Use *NumberForm* to get a precise control over how many significant 
figures are displayed, how many digits after the decimal point, or 
padding characters and the like.

f[x_] := NIntegrate[Sin[y]/y, {y, 0, x}];
OpenWrite["xx.dat", FormatType -> TextForm];
Do[Write["xx.dat", NumberForm[x, {3, 3}], "   ",
    NumberForm[f[x], {3, 3}]], {x, 0.001, 1, 0.05}];
Close["xx.dat"];

will write

0.001   0.001
0.051   0.051
0.101   0.101
0.151   0.151
0.201   0.201
0.251   0.250
0.301   0.299
0.351   0.349
...     ...

Regards,
-- 
Jean-Marc


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