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Re: Clever Tricky Solutions

• To: mathgroup at smc.vnet.net
• Subject: [mg94352] Re: Clever Tricky Solutions
• From: Brett Champion <brettc at wolfram.com>
• Date: Thu, 11 Dec 2008 03:42:56 -0500 (EST)
• References: <27271771.1228394784179.JavaMail.root@m02> <ghavpg$o9j$1@smc.vnet.net> <200812081122.GAA15823@smc.vnet.net> <ghlmek$k3a$1@smc.vnet.net> <200812100949.EAA00324@smc.vnet.net>

On Dec 10, 2008, at 3:49 AM , Helen Read wrote:

> Brett Champion wrote:
>>
>> so I don't think Show has changed much if at all.
>
> Actually, it has changed substantially.
>
> Try this in V5 and V7.
>
> p1 = Plot[x^2, {x, -3, 3}];
> p2 = Plot[-Abs[x - 5], {x, -10, 10}];
> Show[{p1, p2}]
>
> And compare Show[{p2,p1}]
>
> Prior to V6, Show did a decent job of combining PlotRanges  
> automatically
> by default.

*Show* did not change.

The output of a typical Plot in V5 used, either implicitly or  
explicitly, PlotRange->Automatic.  When you combine these sorts of  
graphics with Show, you end up with another graphic with PlotRange- 
 >Automatic, and everything works fine.  But that PlotRange->Automatic  
that Show is using for the combined graphic is coming from the plots,  
not from Show.

The output of a typical Plot in V6/7 turns the default setting of  
PlotRange->Automatic into an explicit PlotRange->{{xmin, xmax},{ymin,  
ymax}} for reasons I explained yesterday.  When you combine these  
sorts of graphics with Show, it uses the first PlotRange for the  
combined graphic.  (Likewise for other options like Axes and  
AxesOrigin.)

>>
>> I agree that it would be nice if Show[] could do something better by
>> default, and hopefully it will in a future version.
>
> That would be nice, but I think it does contradict what you said last
> year. At that time, you basically said that the new behavior of Show  
> is
> a feature, not a bug.

As far as I can tell what I said last year:

http://forums.wolfram.com/mathgroup/archive/2007/May/msg01160.html

is pretty much the same as what I'm trying to say this year.

And just because something is behaving as designed doesn't mean it  
can't be improved. :-)

Brett Champion
Wolfram Research

• References:
  • Re: Clever Tricky Solutions
    • From: congruentialuminaire@yahoo.com
  • Re: Clever Tricky Solutions
    • From: Helen Read <hpr@together.net>