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rtd_sensor.fitting

The public fitting API was introduced in rtd-sensor 0.6.0. IEC 60751 R0 fitting is being added for rtd-sensor 0.7.0.

CalibrationObservation

Introduced in: rtd-sensor 0.6.0

CalibrationObservation(
    temperature_c: float,
    resistance_ohms: float,
    weight: float | None = None,
    standard_uncertainty_ohms: float | None = None,
)

weight and standard_uncertainty_ohms are mutually exclusive on one observation.

fit_iec60751_r0

Planned for: rtd-sensor 0.7.0

fit_iec60751_r0(
    observations: Iterable[CalibrationObservation],
    *,
    minimum_temperature_c: float | None = None,
    maximum_temperature_c: float | None = None,
    name: str = "Fitted IEC 60751 RTD",
) -> IEC60751R0FitResult

Fits only the reference resistance R0 while retaining the package's verified IEC 60751 PT-385 characteristic. With two or more distinct temperatures, an omitted model range defaults to the observation span. A single-temperature fit requires an explicit minimum and maximum model temperature.

Explicit range limits describe intended model applicability, not the span of calibration evidence. With an independent basis they may be broader, narrower, or disjoint from the observation span, but they must remain within the supported IEC characteristic range. The evidence retains the observation span separately so this assumption remains visible.

IEC60751R0FitResult

Planned for: rtd-sensor 0.7.0

Fields:

model: IEC60751RTDModel
evidence: IEC60751R0FitEvidence

IEC60751R0FitEvidence

Planned for: rtd-sensor 0.7.0

Key fields include observations, resistance residuals, counts/degrees of freedom, observation span, declared model range, RMS/max residuals, weighting diagnostics, and the fitting method.

fit_polynomial

Introduced in: rtd-sensor 0.6.0

fit_polynomial(
    observations: Iterable[CalibrationObservation],
    *,
    degree: int,
    minimum_temperature_c: float | None = None,
    maximum_temperature_c: float | None = None,
    name: str = "Fitted polynomial RTD",
    coefficient_source: str | None = None,
) -> PolynomialFitResult

Returns a validated polynomial model plus immutable evidence. Raises RTDFitError when observations cannot produce an acceptable deployable model.

PolynomialFitResult

Introduced in: rtd-sensor 0.6.0

Fields:

model: PolynomialRTDModel
evidence: PolynomialFitEvidence

PolynomialFitEvidence

Introduced in: rtd-sensor 0.6.0

Key fields include observations, residuals, degree, counts/degrees of freedom, fit range, RMS/max residuals, weighting diagnostics, condition number, solver, and scaling information.

See Calibration fitting.