remove unused radial undersampling parameter from KTrajectorySunflowerGoldenRpe

[fzimmermann89]

In KTrajectorySunflowerGoldenRpe, you can set an unused undersampling parameter.

I am currently refactoring the acq_info and trajectory calculators.
For now, I will only throw an notimplementederror if the undersampling factor is set to anything but 1.0,
Later on, this parameter should either be removed or implemented.

mrpro/src/mrpro/data/traj_calculators/KTrajectorySunflowerGoldenRpe.py

Line 23 in 82801e6

self.rad_us_factor: float = rad_us_factor

[fzimmermann89]

@ckolbPTB Or am i missing how it is supposed to work?

[ckolbPTB]

Must be left over from something we in the end did not use. Feel free to already remove the parameter during the refactoring.

on a side note: RPE is not a radial trajectory but a Cartesian trajectory

[fzimmermann89]

No I am confused - maybe I misunderstood RPE.

I always thought RPE is readout lines in kz direction going through points in the kx plane that are arranged in a radial pattern.
So you have to do a fft along kz followed by 2d Nufft along kxky

Why is this considered Cartesian?

Are kxky acquired pseudo radial on Cartesian grid points? This would make it a bit difficult to describe the pattern - how do you do the rounding to grid coordinates? There is some ambiguity...