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MathGroup Archive 2000

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parametric equations

  • To: mathgroup at smc.vnet.net
  • Subject: [mg22021] parametric equations
  • From: MAvalosJr at aol.com
  • Date: Thu, 10 Feb 2000 02:26:09 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Hi Everyone:

I have two parameters,x==3 t, and y ==9t^2. I plot them and get my 
parabola.OK.
Then I get my rectangular equation, i.e, y==x^2.
Now I parametrize the rectangular equation ,y==x^2 and I get completely 
different parametric equations. Both plot the same graph. However,when I plug 
in values for t, in the first case,that is,t=Table[{t,{3 t, 9 t^2},{t,4/3}] I 
get x=4 and y =16.
On the other hand when I do the same operation with the parametrized equation,
t=Table[{t,{-1 + t, (-1 + t)^2, {t,4/3}] I get x=0, y=0. I used this very 
simple example because that how I discovered that my parametrization of 
complicated equations was not giving me the same results as the original 
parameters- even thought the graphs coincided. What am I doing wrong?

Manuel


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