ETS_fkine outputs wrong SE3 when sequence of q is passed

[FelipeCybis]

Check here first
Common issues
No related issue was found here.

Describe the bug
Forward kinematics in custom ERobot in version > 1.0.0 now is forced (with try / except) to pass through the Cpp function ETS_fkine
But ETS_fkine does not handle the q parameter as its pythonic fkine does in versions < 1.0 and outputs wrong results when sequence of q is passed.

For example, creating this simple robot in v1.0.2:

import roboticstoolbox as rtb
import numpy as np

robot = rtb.ERobot(
    [
        rtb.Link(rtb.ET.tz()),
        rtb.Link(rtb.ET.tx())
    ]
)
traj = np.array([[0,0],[0,1]])
print(robot.fkine(q=traj))

Gives us the wrong fkine:

0:
   1         0         1         0         
   0         1         0         1         
   0         0         0         1         
   0         0         0         0         
1:
   0         0         0         0         
   0         0         0         0         
   1         0         1         0         
   0         1         0         1  

Following the fkine docstring, that states "Trajectory operation: If q has multiple rows (mxn), it is considered a trajectory and the result is an SE3 instance with m values.", we would expect two SE(3) as a response for the two translations in traj, the first with z=0, x=0 and the second with z=0, x=1, or:

0:
   1         0         0         0         
   0         1         0         0         
   0         0         1         0         
   0         0         0         1         
1:
   1         0         0         1         
   0         1         0         0         
   0         0         1         0         
   0         0         0         1      

The above result is indeed what we get in v0.11.0 with fkine argument fast=False as well as by cloning the bleeding-edge version from commit 07ad125 and putting back on the fast argument so it can skip the ETS_fkine function (which I guess is the fastest workaround for now)

Version information
v1.0.2 and v0.11.0 installed from PyPI
commit 07ad125 from GitHub

Environment (please complete the following information):

• Windows 11 10.0.22621 Build 22621
• Conda version 22.9.0
• Python 3.10.8
  Env created with

conda create -n rtb python=3.10.8
pip install roboticstoolbox-python

[jhavl]

Hey @FelipeCybis, thanks for finding that, it was a tricky one in the end with column-major ordering with 3D arrays. It's been fixed and will be included in the next release

[FelipeCybis]

Awesome, @jhavl! Thanks :)