Subject:
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Re: Mathematical assistance please
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Newsgroups:
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lugnet.cad.dev
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Date:
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Thu, 6 Jan 2005 23:26:46 GMT
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Viewed:
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1973 times
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In lugnet.cad.dev, Ross Crawford wrote:
> In lugnet.cad.dev, Ross Crawford wrote:
> > In lugnet.cad.dev, Kevin L. Clague wrote:
> > > In lugnet.cad.dev, Ross Crawford wrote:
> > >
> > > <snip>
> > >
> > > > > My mistake.... I am using 4-4cyls.dat. rotating them to align them with the
> > > > > S0-S1-S2 plane is what I don't know how to do.
> > > >
> > > > It's hard work, but this page might help
> > > > http://mathworld.wolfram.com/RotationMatrix.html
> > >
> > > Rosco,
> > >
> > > Thanks again. I understand rotation matricies (to some degree), I just don't
> > > know how to come up with the rotation angle needed to twist the 4-4cyls.dat into
> > > the right position.
> >
> > Could you transform the co-ordinate system so that one of it's axes is along the
> > centre-line of the 4-4cyls (in the plane S0-S1-S2), rotate it about that axis so
> > that the longest sise is in the plane, then transform the co-ord system back?
>
> Or maybe another way to look at it (got this from old lecture notes):
>
> Goal: rotate about arbitrary vector A by alpha
> Idea: we know how to rotate about X,Y,Z
>
> So, rotate about Y by beta until A lies in the YZ plane
> Then rotate about X by gamma until A coincides with +Z
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> Then rotate about Z by alpha
>
> Then reverse the rotation about X (by -gamma)
> Then reverse the rotation about Y (by -beta)
Ooooops, I see now I was totally barking up the wrong tree, you need to WORK OUT
the alpha angle, sorry. But transforming the co-ordinate system should still
work.
ROSCO
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Message is in Reply To:
 | | Re: Mathematical assistance please
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| (...) Or maybe another way to look at it (got this from old lecture notes): Goal: rotate about arbitrary vector A by alpha Idea: we know how to rotate about X,Y,Z So, rotate about Y by beta until A lies in the YZ plane Then rotate about X by gamma (...) (20 years ago, 6-Jan-05, to lugnet.cad.dev)
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