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: LogPlot != Plot[Log]

  • To: mathgroup at smc.vnet.net
  • Subject: [mg24281] RE: [mg24266] LogPlot != Plot[Log]
  • From: Wolf Hartmut <hwolf at debis.com>
  • Date: Fri, 7 Jul 2000 00:11:24 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

> -----Original Message-----
> From:	Gy. Csanady [SMTP:csanady at gsf.de]
To: mathgroup at smc.vnet.net
> Sent:	Thursday, July 06, 2000 5:11 AM
> To:	mathgroup at smc.vnet.net
> Subject:	[mg24266] LogPlot != Plot[Log]
> 
> Dear Steve Christensen,
> 
> I should like to post the following question to the Mathgroup. I am
> relatively new with Mathematica and I encountered a problem..
> 
> 
> Dear MathGroup,
> I should like to demonstrate some transformation rules graphically using
> Mathematica extended capabilities. However, the simplest example failed:
> Let assume a simple exponential function with real parameters:
> 
> C1[t_] := C0*Exp[-kel*t]
> 
> param = {C0 -> 100, kel -> 1}
> 
> we can plot the function easily:
> 
> g1 = Plot[C1[t] /. param, {t, 0, 2}, PlotRange -> {{0, 2}, {10, 100}}]
> 
> 
> We can also make a half- logarithmic plot:
> 
> g2 = Plot[Log[E, C1[t]] /. param, {t, 0, 2}, PlotStyle -> {RGBColor[0, 0,
> 1],
> Dashing[{0.05, 0.05}]},  PlotRange -> {{0, 2}, {Log[10], Log[100]}}]
> 
> In addition we can convert the y-axis to a logarithmic one:
> 
> g3 = Show[g2, Ticks -> Join[{FullOptions[g2, Ticks][[1]], FullOptions[g2,
> Ticks][[2]] /. {x_, y_Real, len_, style_} :> {x, Exp[y], len, style}}]]
> 
> We can obtain a half-logarithmic plot by using the LogPlot function:
> 
> << Graphics`Graphics`
> 
> g4 = LogPlot[C1[t] /. param, {t, 0, 2}, PlotRange -> {{0, 2}, {10, 100}}]
> 
> Now I would expect that plot g4 and g3 become identic:
> 
> Show[{g3, g4}, PlotRange -> All]
> 
> But it is not the case. I am sure that there is something wrong. Any help
> would be appreciated.
> With best regards
> Gy. Csanady
> 
> 
[Wolf Hartmut]  

There is no mystery here, you only need base 10 for the logarithm. See
  
In[9]:=
g2a = Plot[Log[10, C1[t]] /. param, {t, 0, 2}, 
    PlotStyle -> {RGBColor[1, 0, 1], Dashing[{0.05, 0.07}],
Thickness[0.01]}, 
    PlotRange -> {{0, 2}, {Log[10, 10], Log[10, 100]}}]

In[10]:=
g3a = Show[g2a, 
    Ticks -> Join[{FullOptions[g2a, Ticks][[1]], 
          FullOptions[g2a, Ticks][[2]] /. {x_, y_Real, len_, style_} :> {x, 
                10^y, len, style}}]]

and then

In[16]:= Show[{g4, g3a}]

However 

In[15]:= g3d = Show[g2a, Ticks -> {Automatic, LogScale[1, 2]}]

In[17]:= Show[{g3d, g4}]

is less work!

Kind regards, 
Hartmut Wolf


  • Prev by Date: RE: Re: 1/Trig function - help
  • Next by Date: "Best" ComplexityFunction Setting ?
  • Previous by thread: Re: LogPlot != Plot[Log]
  • Next by thread: Re: Piecewise functions definition and usage