Re: a problem about mathematica output
- To: mathgroup at smc.vnet.net
- Subject: [mg82422] Re: a problem about mathematica output
- From: Szabolcs Horvát <szhorvat at gmail.com>
- Date: Sat, 20 Oct 2007 05:44:36 -0400 (EDT)
- 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}];
You don't need the ; here ... -------^
> OpenWrite["xx.dat",FormatType->TextForm];
> Do[Write["xx.dat",N[x,4]," ",N[f[x],4]],{x,0.001,1,0.05}];
... or here -------------------------------------------------^
> 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!
Try to avoid procedural constructs such as Do[] when using Mathematica.
They have their uses, but Table and Exports are a better fit for this
problem:
dat = Table[{x, NIntegrate[Sin[y]/y, {y, 0, x}]}, {x, .001, 1, .05}]
Export["xx.dat", Round[dat, 0.001], "Table"]
Truncating the result to only 3 digits might not be a very good idea, so
if you are doing this only to *look* at the numbers, then try
NumberForm[dat // TableForm, 3]
--
Szabolcs