Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2006
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2006

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: computing times and output display

  • To: mathgroup at smc.vnet.net
  • Subject: [mg66955] Re: [mg66923] computing times and output display
  • From: Daniel Lichtblau <danl at wolfram.com>
  • Date: Mon, 5 Jun 2006 03:48:01 -0400 (EDT)
  • References: <200606040509.BAA13008@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Steven Shippee wrote:
> Running Mathematica version 5.2 on Windows XP Professional with an older 
> Pentium III 833MHz processor and 512 GB of RAM.
> 
> Anyone know why 8^8^8 (or 9^9^9) takes several minutes to "compute" and 
> display results, but in a new fresh kernel/environment 9^9^9. (decimal after 
> the last number 9) one gets an almost instantaneous response?  Is this 
> merely the difference in preparing for the output of the computation to the 
> screen ...
> 
> Thanks in advance,
> 
> Steven Shippee 
> 

Yes and no, respectively.

8^8^8, being a power of 2, is computed quite fast.

In[1]:= Timing[a=8^8^8;]
Out[1]= {0.004, Null}

Formatting suitable for output involves a hex-to-decimal conversion. One 
can see this by writing it to a string.

In[7]:= Timing[as = ToString[a,InputForm];]
Out[7]= {55.6395, Null}

The case of 9^9^9 is slow in both directions. More so for output 
preparation because that involves division rather than multiplication by 
large numbers.

Working with a numeric approximation is going to be very fast, among 
other reasons, because only a few significant digits are maintained.


Daniel Lichtblau
Wolfram Research


  • Prev by Date: Re: Packages--guikit and mathgl3d help!
  • Next by Date: Caret
  • Previous by thread: computing times and output display
  • Next by thread: computing times and output display