The following may be of some help, but I notice that my results are
slightly different from yours with regard to with yaw and roll type
rotations. Our "pitch" rotations seem to agree. The difference seems to be
mostly in the definition of my ry0. These are all taken from my turtle
graphics for j (tgfj) development.
load'trig'
I3 =: =@i. 3
i3 =: I3"_
rx0=: (cos,sin),:(-@sin,cos)
ry0 =: (cos,-@sin),:(sin,cos)
ry0 =: rz0 =: rx0
'RlRow YwRow PtRow' =: i. 3
AllRow =: i. 3
PtPlane =: 1 2
YwPlane =: 0 1
RlPlane =: 2 0
bip=: <"1@(,"0/~) NB. Table of boxed index pairs
bipx =: (bip PtPlane)"_
bipy =: (bip RlPlane)"_
bipz =: (bip YwPlane)"_
rx=: ''&(rx0@]`bipx`i3})"0
ry=: ''&(ry0@]`bipy`i3})"0
rz=: ''&(rz0@]`bipz`i3})"0
ptRot =: rx
rlRot =: ry
ywRot =: rz@:-
ywRot 0.05p1
0.987688 _0.156434 0
0.156434 0.987688 0
0 0 1
ptRot 0.05p1
1 0 0
0 0.987688 0.156434
0 _0.156434 0.987688
rlRot 0.05p1
0.987688 0 0.156434
0 1 0
_0.156434 0 0.987688
On Sun, Jul 10, 2016 at 1:43 PM, Raul Miller <[email protected]> wrote:
> I need a routine which makes rotation matrices for a given angle.
>
> For example, let's say that my angle is 0.05p1, I would be wanting
> these two rotation matrices:
>
> 3 3$(2 1 o./ (,-)0.05p1) 0 4 1 3}&,=i.3
> 0.987688 0.156434 0
> _0.156434 0.987688 0
> 0 0 1
>
> and
>
> 3 3$(2 1 o./ (,-)0.05p1) 4 8 5 7}&,=i.3
> 1 0 0
> 0 0.987688 0.156434
> 0 _0.156434 0.987688
>
> Now, obviously, I could implement this directly:
>
> rotmat=:dyad define
> 3 3$(2 1 o./ (,-)y) (0 4 1 3+4*x)}&,=i.3
> )
>
> But it seems to me that there ought to be a better way of doing this.
> And by better I mean more concise and direct.
>
> But I'm not seeing that.
>
> The best alternative I have thought of so far is:
>
> elcric=:dyad define"0
> if. 1<|y do.
> (_2+|y) o. x**y
> else.
> y
> end.
> )
>
> rotmat=:dyad define
> (1 1-x) |. y elcric 1 0 0,0 4 3,:0 _3 4
> )
>
> And while maybe that satisfies some concept of "prettier" it is not
> more concise and it is not more direct. It is not even faster.
>
> That said, what I really want to build would be this:
>
> rotate=:monad define
> +/ .*/ 0 1 0 rotmat"0 y+0 0 0
> )
>
> (I threw in the unnecessary +0 0 0 to emphasize that I expect three
> angles.)
>
> In other words, I have three different euler angles and I want the
> rotation matrix they represent. So maybe there is even something
> already implemented for this purpose? (But when I search jsoftware.com
> for mentions of euler angles, I don't see anything promising.)
>
> Any ideas?
>
> Thanks,
>
> --
> Raul
>
> P.S. I imagine I could live with getting the rotation quaternion they
> represent, instead of the rotation matrix. But I have not investigated
> the details of that approach here.
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
--
(B=) <-----my sig
Brian Schott
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
