spc_capability — SPC `capability` op

• Data kinds: signal → table

• Call: import fullseye as fs; fs.ledger.spc_capability(signal, lsl, usl, sigma=None) (to call the implementation directly, import spc; spc.spc_capability(signal, lsl, usl, sigma=None); from the registry, opsspc.get("spc_capability"))

Usage

Process capability indices Cp and Cpk from measurements and spec limits.

`signal is a 1-D series of individual measurements; lsl / usl` are the

lower / upper specification limits (`lsl < usl). With the sample mean mu`

and standard deviation `sigma (sample std, ddof=1`, unless one is passed

in explicitly)::

Cp = (USL - LSL) / (6 sigma)

Cpk = min(USL - mu, mu - LSL) / (3 sigma)

Returns a dict with `mean / std / cp / cpk` and the echoed spec

limits and midpoint. `Cpk <= Cp` always, with equality exactly when the

process is centred (`mu` at the spec midpoint) — pinned in the tests.

Raises `ValueError`: a non-1-D / empty *signal*, fewer than two points

(no spread to estimate), `lsl >= usl`, non-finite limits, or a non-positive

standard deviation (a constant series has no capability to report).

References (sample data, literature)

• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).

• Operator provenance and references — the sources of the research/methods this op family came from.

• The canonical algorithm (author, year) and its uses are named in the family usage guide above.

Runnable examples (verified samples that actually call this op)

• poc_spc — py -3.11 examples/poc_spc.py

Ops the type connects to (they accept `table` as input)

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Same category (`capability`)

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*Provenance: spc.py — SPC operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

spc_capability — SPC capability op