Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2000
*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 2000

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

Search the Archive

Re: entering an equation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg21629] Re: [mg21592] entering an equation
  • From: "Tomas Garza" <tgarza at mail.internet.com.mx>
  • Date: Tue, 18 Jan 2000 02:35:16 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Mark Woolard [mark at ratbyte.com] wrote:

> I am trying to plot a series of functions in Mathematica...one is
> giving me
> trouble. I need : ln2 (ln2 x)
>
>     I enter: Log[2, Log[2,x]]
>
> and I get:
>
> is not a machine-size real \
> number at \!\(x\) = \!\(4.1666666666666667`*^-7\)."
>
> Does anyone have any suggestions?

Yes. The range over which you wish to plot is important. Try, for example:

In[1]:=
Plot[Log[2, Log[2, x]], {x, 1, 2}]

The plot is OK. Look at the values of ln2 (ln2 x) in the neighborhood of 1 +
0:

In[2]:=
Table[Log[2, Log[2, x]], {x, 1, 2, 0.1}]
Out[2]=
{-Infinity, -2.86246, -1.92668, -1.40159, -1.04267, -0.773584, -0.56049, \
-0.38546, -0.237869, -0.110917, 0.}

Tomas Garza
Mexico City



  • Prev by Date: InterpolatingFunction in NDSolve
  • Next by Date: Re: Mathematica???
  • Previous by thread: Re: entering an equation
  • Next by thread: Re: generating subsets