Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2010

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

Search the Archive

Re: change the base of the Log[] used by LogLogPlot?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg112946] Re: change the base of the Log[] used by LogLogPlot?
  • From: "Nasser M. Abbasi" <nma at 12000.org>
  • Date: Thu, 7 Oct 2010 03:36:41 -0400 (EDT)

On 10/6/2010 9:15 AM, Brett Champion wrote:
> On Oct 6, 2010, at 11:07 AM, Nasser M. Abbasi wrote:
>
>> On 10/6/2010 8:29 AM, Brett Champion wrote:
>>> On Oct 6, 2010, at 2:15 AM, Nasser M. Abbasi wrote:
>>>
>>>> Mathematica experts:
>>>>
>>>> I want to use LogLogPlot, say as in LogLogPlot[x,{x,.1,1}], but I
>>>> want
>>>> the Log to be in base 10, not in base e as the default used.
>>>>
>>>> Looking at the doc, I can't see it. No option to change the base.
>>>>
>>>> I can ofcourse build my own data, and use ListPlot, but LogLogPlot
>>>> handles the ticks better automatically and it samples better. Same
>>>> question applies for LogPlot, LogLinearPlot, ListLogPlot,
>>>> ListLogLinearPlot, etc...
>>>>
>>>> I am sure this is hidden somewhere in the documentation :)
>>>>
>>>
>>
>>> Nope.  LogPlot uses Log.
>>>
>>> I'm curious as to why you want to switch to Log10 since the plot
>>> would
>>> end up looking exactly the same.
>>>
>>
>>
>> But not if x is linear and y is log, then the plot are not the same:
>>
>> ----loglinear-------
>> x = {1, 2, 3, 4};
>> data1 = Table[{x, Log[10, x]}, {x, 1, 10}];
>> data2 = Table[{x, Log[x]}, {x, 1, 10}];
>> Show[{ListPlot[data1, PlotStyle ->  Red, Joined ->  True],
>>    ListPlot[data2, Joined ->  True]}]
>> ---------------------
>>
>> any way, not too important, just was wondering ;)
>


> My point is that these look the same:
>
> {ListPlot[data1, PlotStyle ->  Red, Joined ->  True],
>    ListPlot[data2, Joined ->  True]}
>
> (ignoring the ticks which get adjusted anyway.)
>
> Brett Champion
> Wolfram Research
>

When you say "these", you seem to have used the loglog version. Yes.

But when x is linear, and y is log (like Mathematica LogPlot), then 
different bases used for the log make a different looking plots.  (how 
can y=log(10,x) = log(x) ?), different y values for same x value result:

Please see screen shot.

http://12000.org/tmp/oct62010/Untitled.png

For the loglog, yes, becuase both are scaled same way. But then have to 
adjust ticks.

Thanks,

--Nasser


  • Prev by Date: Re: suggestions for version control or backup systems?
  • Next by Date: Re: How to interpolate vectors?
  • Previous by thread: Re: change the base of the Log[] used by LogLogPlot?
  • Next by thread: Find minimum number of operations