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MathGroup Archive 2006

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Newbie: Rotataion2D use problem

  • To: mathgroup at smc.vnet.net
  • Subject: [mg66675] Newbie: Rotataion2D use problem
  • From: akil <akil39 at gmail.com>
  • Date: Sat, 27 May 2006 03:50:43 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

I have some problems using Mathematica's Rotate2D, it doesnot give the results as I want them 

Eample:

a={10, 30}
b={80., 0.}
c={38.7689, 0.}
theta = -0.24497866312686414`
theta2 = -0.3430239404207034`
Rotate2D[a, theta, test[[1]]]
Rotate2D[%, theta2, test[[2]]]

this gives:
\!\({2.7134309891835002`, 1.7763568394002505`*^-15}\)

While the y-value should be 0 instead of 1.7763568394002505`*^-15.

Anyone know how I can easily fix this, so that I get 0 here instead?

Explanation of reasoning: I need to rotate points about points so that they have the same values, and sometimes like here there are a couple of rotations about points needed, and I always get these weird values, but I reeally need them to be 0 for further research purposes.

(By the way, thanks to all people that replied to my previous post, still need to decide on which one to use, but the problem got a bit harder there, by some complications that are now involved, something to do with clockwise order of found points.)

Akil


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