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Re: Re: A New Scientist article verified with Mathematica

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  • Subject: [mg107318] Re: [mg107271] Re: A New Scientist article verified with Mathematica
  • From: John Fultz <jfultz at>
  • Date: Tue, 9 Feb 2010 02:44:24 -0500 (EST)
  • Reply-to: jfultz at

On Sun, 7 Feb 2010 06:14:31 -0500 (EST), sigismond kmiecik wrote:
> sigismond kmiecik a E9crit :
>> Hello to everybody
>> In  the last Xmas issue of the New Scientist magazine there is on page
>> 40 a small article about the continuity principle applied to
>> intersecting circles.
>> I used Mathematica to confirm its conclusions but some questions remain
>> to be answered.
>> These circles are represented by
>> Show[{Graphics[{Red, Circle[{0, 0}, 2]}], Graphics[Circle[{2, 0}, 2]],
>> Graphics[{Red, Dashed, Circle[{5, 0}, 2]}]}, AxesOrigin -> {0, 0},
>> PlotRange -> {{-3, 8}, {-3, 3}}, Axes -> True ]
>> The intersection coordinates of the red (non-dashed) and black circle is
>> found by:
>> Solve [{ x^2 + y^2 - 4 == 0, (x - 2)^2 + y^2  - 4  == 0 }, {x, y}
>> ]
>> And there is indeed an imaginary intersection of the red and red-dashed
>> circle even if they are not touching -  as found by:
>> Solve [{ x^2 + y^2 - 4 == 0, (x - 5)^2 + y^2  - 4  == 0 }, {x, y}
>> ]
>> My questions are:
>> - Is there a way to draw  with Mathematica these three circles using
>> their cartesian equations and not the Circle graphics primitive
> 92 ?
>> - How can I transform the list of rules solutions to the last equation
>> above  in order to represent them on the complex plane  (I thought about
>> a ListPlot [{Re[],Im[]}=85  but I know not  enough of Mathematica to
>> obtain that)
>> - And last is there a Mathematica notebook on the web dealing with the
>> intersection of  planes with cones?
>> Thanks
>> Sigismond Kmiecik
> Hi
> THe two Solve expressions that I copied/pasted from a Mathematica
> notebook to Thunderbird
> became corrupted after being  added to the forum. What precautions must
> I take in order to
> avoid that ?
> Thanks
> Sigismond Kmiecik

The corruption I saw was an = sign at the end of some of the lines.  That's what 
you saw too, right?  This doesn't have anything to do with Mathematica, as you 
may have suspected.

I'm not for certain, but I strongly suspect that this generally is caused by
sending some sort of combined HTML/plain-text email to the list, and the process 
that Steve uses when moderating/forwarding to the list to strip it down to plain 
text (which is the only format he'll ever post onto the forum...a decision I
happen to support, incidentally).  The extra markings look like MIME markup of 
the type that gets included when you have combined messages like that.

I think that if you set Thunderbird to send email as plain text only, you 
wouldn't see this problem.

[Many posts that have either html or non-ascii characters in them may
get corrupted during processing.  It is best to make sure posts have
no html in them or as attachments and no non-ascii contents - moderator]


John Fultz
jfultz at
User Interface Group
Wolfram Research, Inc.

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