Dipole and quadrupole field flips for any field format

[Laurie Nevay]

Currently, the dipole and quadrupole field reflection that take 1/4 or 1/8th respectively of a field map and flip it (with appropriate sign flips for each quadrant or octant) are only used with the Poisson SuperFish field formats. The underlying classes can however be used with any array once loaded.

I propose to make it such that the any field once loaded can be flipped in such a way.

Use case: Opera2D fields for 1/4 of H-dipole converted to BDSIM but can't be reflected.

[Laurie Nevay]

Moreover, it'd be good to have a general flip (ie reversal) for each dimension which I think is pretty easy to implement now.

[Jochem Snuverink]

Maybe I misunderstood the proposal, but it would be nice to have some symmetry options for every field map. A symmetry around the middle plane is quite common.

[Laurie Nevay]

Yes, symmetry options would be good. So, it’s not just using -y → y for the query, the field field queried also has to be flipped. If we take this figure as an example:

http://www.pp.rhul.ac.uk/bdsim/manual/dev_fields.html#multipole-yoke-dipole

If we had a field map only for the top half and wanted to have a symmetry with the bottom half - so a mid plane symmetry, a point at say x,y = -50,-50 should have +Bx, +By. Taking the point at -50,+50 would be -Bx, +By. So we must also flip the x component of the field 3 vector. If it’s a 1/4 segment (e.g. one pole of a quadrupole) then the flips also depend on the quadrant too. This is written for the poisson superfish field formats but should be generalised for all field maps.

Certainly it would save memory for field maps!

[Laurie Nevay]

Forgot about this issue number - I’m writing in Issue #310 now. Nearly finished implementing it.

[Laurie Nevay]

Implemented in develop now and will be in release V1.7.0.