MathGroup Archive 2006

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Newbie: Rotataion2D use problem

  • To: mathgroup at
  • Subject: [mg66738] Re: [mg66675] Newbie: Rotataion2D use problem
  • From: gardyloo <gardyloo at>
  • Date: Sat, 27 May 2006 21:04:27 -0400 (EDT)
  • References: <>
  • Sender: owner-wri-mathgroup at

Hi, Akil,

     Although I don't know what your function "test" is, so can't 
reliably reproduce the results, you might try passing it as the argument 
to "Chop", so that, for example,


Chop[{2.7134309891835002, 1.7763568394002505*^-15}]


{2.7134309891835002, 0}

                      Hope that helps,

akil wrote:
> 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

Curtis Osterhoudt
PGP Key ID: 0x088E6D7A
Please avoid sending me Word or PowerPoint attachments

  • Prev by Date: Re: Simplification and Arg[]
  • Next by Date: Re: M100: An Introduction To Mathematica
  • Previous by thread: Newbie: Rotataion2D use problem
  • Next by thread: Re: Newbie: Rotataion2D use problem