yade-users team mailing list archive

[Václav Šmilauer <eudoxos@xxxxxxxx>]

-------- Original Message --------
Subject: 	Re: [Yade-users] Questions on equations (contact laws,
velocity, libraries)
Date: 	Wed, 09 Dec 2009 16:59:52 +0100
From: 	Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>
To: 	Václav Šmilauer <eudoxos@xxxxxxxx>


>> Q2. Why are we using the approximated rotations in updating Shear, and
>> not quaternions.  It has been commented out in many files.  Is there
>> sth that I'm not aware of?
>>     
> I have no idea, but it was written by Olivier and I wouldn't trust it
> (ok, I know this has become cliche in a way...; you can take it as a
> joke as well). I think the real reason is that for the incremental
> formulation, you don't need exact rotations since they cost too much and
> the linearized form is sufficient. Bruno?
>
>   
Agreed.

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