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: [mg21608] Re: [mg21592] entering an equation
  • From: "David Park" <djmp at earthlink.net>
  • Date: Sun, 16 Jan 2000 22:43:53 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

>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?
>


Mark,

Plot[Log[2, Log[2, x]], {x, 1.0, 10}]; works but

Plot[Log[2, Log[2, x]], {x, 0.99, 10}]; does not work because you are trying to take
a log of a negative number over the first part of the range.  Mathematica will
produce the plot over the domain where the function is real. So you can either ignore
the error messages, or turn them off, or restrict your plotting domain to a proper
range of numbers which give only real and not complex results.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/



  • Prev by Date: Re: generating subsets
  • Next by Date: Series expansion of ArcSin around 1
  • Previous by thread: Re: entering an equation
  • Next by thread: Re: entering an equation