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 23:23:51 GMT
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Viewed:
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2097 times
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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
Then rotate about Z by alpha
Then reverse the rotation about X (by -gamma)
Then reverse the rotation about Y (by -beta)
ROSCO
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Message has 2 Replies:
 | | Re: Mathematical assistance please
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| (...) 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 (20 years ago, 6-Jan-05, to lugnet.cad.dev)
| | | Re: Mathematical assistance please
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| (...) OK, here's my VERY LAST word on the subject: Transforming both 4-4cyls S0-S1 and vector S1-S2: Rotate about Y by beta until S0-S1 lies in the YZ plane Rotate about X by gamma until S0-S1 coincides with +Z Rotate about Z by delta until S1-S2 (...) (20 years ago, 7-Jan-05, to lugnet.cad.dev, FTX)
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Message is in Reply To:
| | Re: Mathematical assistance please
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| (...) 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? (...) (20 years ago, 6-Jan-05, to lugnet.cad.dev)
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