Calibrated Age Intercept Range

Intersect a measured radiocarbon uncertainty band with a supplied piecewise-linear calibration curve, retaining disjoint intervals; not Bayesian calibration, curve uncertainty or an embedded IntCal lookup.

Description

Radiocarbon calibration curves can map one measurement band to several calendar-age intervals.

Radiocarbon calibration curves can map one measurement band to several calendar-age intervals. Preserving disconnected intersections avoids replacing a multimodal result with one misleading continuous span.^[1]

When to use Calibrated Age Intercept Range

Use this tool to intersect a measured radiocarbon uncertainty band with a supplied piecewise-linear calibration curve, retaining disjoint intervals; not Bayesian calibration, curve uncertainty or an embedded IntCal lookup.

Prepare the artifact, site or survey measurements and any independently established calibration or model choices. Keep paired observations aligned and confirm units and coordinate conventions.

How to use Calibrated Age Intercept Range and understand its results

Prepare the artifact, site or survey measurements and any independently established calibration or model choices. Keep paired observations aligned and confirm units and coordinate conventions.
Enter calendarAgesBp, curveRadiocarbonAgesBp, measuredRadiocarbonAgeBp, measurementSigmaYears, sigmaMultiplier using the field table and calculation rules, then run the tool.
Read calendarAgeIntervalsBp. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
calendarAgesBp	Calendar ages bp	list of number	Required
curveRadiocarbonAgesBp	Curve radiocarbon ages bp	list of number	Required
measuredRadiocarbonAgeBp	Measured radiocarbon age bp	number	Required
measurementSigmaYears	Measurement sigma years	number	Required
sigmaMultiplier	Sigma multiplier	number	Required

Pair at least two increasing calendar ages BP with finite curve radiocarbon ages BP, and supply positive measurement sigma and multiplier. Intersect the band with every linear curve segment, retaining flat segments inside it and boundary ties. Merge touching intervals, retain disconnected ones and reject no intersection. Return up to 128 calendar-age intervals within the supplied curve domain.

Paired lists must be nonempty and have equal lengths. Each sequence checked for increasing order must contain at least two strictly increasing values.

measurement band = measuredAge ± sigmaMultiplier × measurementSigma

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
calendarAgeIntervalsBp	Calendar age intervals bp	list of list of number

json

{
  "input": {
    "calendarAgesBp": [
      0,
      100,
      200,
      300
    ],
    "curveRadiocarbonAgesBp": [
      0,
      100,
      0,
      100
    ],
    "measuredRadiocarbonAgeBp": 50,
    "measurementSigmaYears": 10,
    "sigmaMultiplier": 1
  },
  "output": {
    "calendarAgeIntervalsBp": [
      [
        40,
        60
      ],
      [
        140,
        160
      ],
      [
        240,
        260
      ]
    ]
  }
}

Limitations and assumptions

The caller supplies the curve; no IntCal table is embedded. This is band interception, not Bayesian calibration or a probability distribution. Curve uncertainty and extrapolation are excluded.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Numeric lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Marine Reservoir Correction: Subtract supplied regional reservoir age plus local delta-R and propagate independent uncertainties; corrected ages can be signed and are not calendar-calibrated ages. For a complementary task, use Stratum Depth Interpolation: Interpolate a supplied monotone stratigraphic depth-age model within bracketed control points; no extrapolation, reversals, hiatus uncertainty or sedimentation-rate inference.

References

Calibrated Age Intercept Range — tool.io

Similar or alternative tools

Marine Reservoir Correction
Subtract supplied regional reservoir age plus local delta-R and propagate independent uncertainties; corrected ages can be signed and are not calendar-calibrated ages.
Stratum Depth Interpolation
Interpolate a supplied monotone stratigraphic depth-age model within bracketed control points; no extrapolation, reversals, hiatus uncertainty or sedimentation-rate inference.