Re: [eigen] Euler-angles and partial reductions API design

```Ah OK, I didn't realize that. Thanks for the explanation.

Benoit

On Saturday 19 July 2008 00:58:30 Gael Guennebaud wrote:
> well, I would prefer to keep the AngleAxis class, for various reasons.
> One of them is that we also have the Quaternion, so you create an
> angle axis and it gets automatically converted to whatever you want:
>
> Quaternion q = AngleAxis(a,b);
> Matrix m = AngleAxis(a,b);
>
> that is pretty nice IMO, and Matrix3f::Rotation(a,b)  will never be as
> explicit as AngleAxis(a,b), isn't it ?
>
> I also have to say that since two angle-axis cannot be directly
> composed, AngleAxis(a,b) * AngleAxis(c,d) must convert the two
> operands to a quaternion or a matrix. In practice, converting them to
> Quaternion is always faster even if at the end you want a matrix (and
> even if you have special AngleAxis to rotation matrix conversion
> functions for rotation around basis axes).
>
> gael.
>
> > one more remark,
> >
> > if we drop EulerAngles then we can also drop the AngleAxis class in favor
> > of just "rotation" functions, not classes. so the above snippet becomes
> >
> > Matrix3f m2 = Matrix3f::rotation(a1, Vector3f(1,0,0))
> >              * Matrix3f::rotation(a2, Vector3f(0,1,0))
> >              * Matrix3f::rotation(a3, Vector3f(0,0,1));
> >
> > I think that's nicer!
> >
> > Cheers,
> > Benoit

```

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