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: Vertical Tangents

  • To: mathgroup at smc.vnet.net
  • Subject: [mg25816] Re: [mg25787] Vertical Tangents
  • From: "Tom De Vries" <tdevries at shop.westworld.ca>
  • Date: Sat, 28 Oct 2000 01:41:08 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Hello!

I would also be interested in the ImplicitPlot "solution" to the question
given below.  The way I would get these graphs is really messy so I figure
someone knows a better way!  This is just a "quick fix" answer...

To do these kinds of plots, I have used ContourPlot with options set to  get
what I want.  The line below produces the plot.  The Block and Display
Function "mess" are not needed if you use the DrawingPaper package created
by David Park  (which is excellent!)


Block[{$DisplayFunction = Identity}, 
    graph1 = ContourPlot[x^2 + x*y + y^2 - 7 , {x, -5, 5}, {y, -5, 5}, 
        ContourShading -> False, Contours -> {0}, Frame -> False, 
        Axes -> True, AxesOrigin -> {0, 0}];
    graph2 = 
      ContourPlot[y - 2*Sqrt[7/3], {x, -5, 5}, {y, -5, 5}, 
        ContourShading -> False, Contours -> {0}, Frame -> False, 
        Axes -> True, AxesOrigin -> {0, 0}];
    graph3 = 
      ContourPlot[ x - 2*Sqrt[7/3], {x, -5, 5}, {y, -5, 5}, 
        ContourShading -> False, Contours -> {0}, Frame -> False, 
        Axes -> True, AxesOrigin -> {0, 0}];
    ];
Show[{graph1, graph2, graph3}, DisplayFunction -> $DisplayFunction];



Sincerely,

Tom De Vries


----------
>From: Tom Moriarty <tjmor at erols.com>
To: mathgroup at smc.vnet.net
>To: mathgroup at smc.vnet.net
>Subject: [mg25816] [mg25787] Vertical Tangents
>Date: Wed, Oct 25, 2000, 12:53 AM
>

>This group was very helpful on my last question and I hope you will be
>willing to once again come to the aid of a teacher trying to illustrate
>to calculus students tangents to implicit plots.  By the way, I
>purchased Mathematica on my own, it is not available to me at school -
>so I plot at home and Xerox handouts for the kids.  I have been able to
>show them various implicit plots and tangents to them - for example
>ImplicitPlot[{x^2 + x*y + y^2==7, y == 2*Sqrt[7/3]},{x,-5,5}] which
>clearly shows the ellipse and one of the horizontal tangents (as asked
>for in the textbook problem).  But the problem also asked for the
>vertical tangents, one of which would be x == 2*Sqrt[7/3], but I get the
>message that this equation does not have a single variable other than
>x.  Is there any way to plot a vertical line?
>
>Let me tell you Mathematica certainly has helped my students (and me)
>visualize these implicit plots, without which they are just a matter of
>faith.
>
>Any help you can give me will be greatly appreciated.
>
>Tom Moriarty
>
>
>
>



  • Prev by Date: RE: Adding a new style environment
  • Next by Date: Question concerning Mathematica packages
  • Previous by thread: Re: Vertical Tangents
  • Next by thread: LeafCount Question