fix: change coordinate system consistently #277
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nvaytet
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Nov 11, 2025
| open=ch.slit_begin, | ||
| close=ch.slit_end, | ||
| phase=abs(ch.phase), | ||
| phase=ch.phase if ch.frequency.value > 0.0 else -ch.phase, |
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If you change the order of operations in tof, does this go away?
(first add phase, and then mirror)
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No I could not make it go away by changing anything in tof.
I lean towards the implementation in tof being correct.
| phase=abs(ch.phase), | ||
| phase=ch.phase if ch.frequency.value > 0.0 else -ch.phase, | ||
| distance=sc.norm(ch.axle_position - source_position), | ||
| name=name, |
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Maybe we should add properly maintained methods in tof to construct chopper from DiskChopper and NeXus.
I suspect this code exists in multiple places (packages, notebooks etc...)
See scipp/tof#6.
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Yeah that sounds like a good idea. Do you want to see that in this PR?
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Do you want to see that in this PR?
No, I will do that separately.
nvaytet
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Nov 11, 2025
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Fixes #263
If the frequency is negative we change the direction of the coordinate system to make it positive.
In that case, phase should also be transformed the same way, but phase should not be transformed just because it is negative.