Fix poly_fit signature to work with ProcessingChain

[Copilot]

The poly_fit factory function had an incorrect GUFuncWrapper signature "(n),(m)" which was parsed as 2 inputs / 0 outputs instead of 1 input / 1 output. This broke DSP configs using poly_fit with build_dsp().

Changes

• Fix signature: "(n),(m)" → "(n)->(m)" to correctly indicate input/output dimensions
• Fix types: ["ff", "dd"] → ["ff->f", "dd->d"] to match signature format
• Add docstrings: YAML configuration examples for poly_fit, poly_diff, poly_exp_rms

Example Configuration

tail_pars:
  function: poly_fit
  module: dspeed.processors
  args:
    - wf_logged[(db.tail.start):(db.tail.stop)]
    - tail_pars(5, 'd')
  init_args:
    - len(wf_logged[(db.tail.start):(db.tail.stop)])
    - '4'
  unit: ADC
  defaults:
    db.tail.start: 2125
    db.tail.stop: 4000
tail_slope: tail_pars[1]

Original prompt

I don't understand how to use poly_fitter anymore. Previosly I would provide build_dsp() with a dsp config file containing the following:

tail_pars:
description: Look at the tail of the waveform. Start once the windowed waveform
ends and go until the end. Get values for where the tail starts and ends from
database (Usually, however that means starting at 85 us and continuing until
160 us).
function: poly_fit
module: dspeed.processors
args:
- wf_logged[(db.waveform_presummed.tail.start):(db.waveform_presummed.tail.stop)]
- tail_pars(5, 'd')
init_args:
- len(wf_logged[(db.waveform_presummed.tail.start):(db.waveform_presummed.tail.stop)])
- '4'
unit: ADC
defaults:
db.waveform_presummed.tail.start: 2125
db.waveform_presummed.tail.stop: 4000
tail_slope: tail_pars[1]
tail_diff, tail_rms:
description: finds residual of quadratic fit of the logged tail
function: poly_exp_rms
module: dspeed.processors
args:
- waveform_presummed[(db.waveform_presummed.tail.start):(db.waveform_presummed.tail.stop)]
- tail_pars
- tail_diff
- tail_rms
unit:
- ADC
- ADC
defaults:
db.waveform_presummed.tail.start: 2125
db.waveform_presummed.tail.stop: 4000

Recently, poly_fitter changed and my config does not work anymore. Can you figure out
a) How to change the config to make build_dsp() work again
b) How poly_fitter works now and provide documentation?

Any questions? Something unclear?

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