Threshold Downcrossing Indexes
Find down crossings from strictly above to the threshold-or-beyond; equality plateaus do not repeatedly trigger.
Description
Find down crossings from strictly above to the threshold-or-beyond; equality plateaus do not repeatedly trigger.
A sampled downcrossing is a transition from strictly above a threshold to at or below it. Its index identifies the arrival sample rather than an interpolated crossing time.
When to use this tool
Find down crossings from strictly above to the threshold-or-beyond; equality plateaus do not repeatedly trigger.
- Prepare the supplied values, threshold fields for this operation.
- Compare the complete example with the representation used by your own input before carrying the result into another step.
How to use the tool and how it works
- Enter values, threshold. Use the exact text syntax, units and index conventions explained below.
- Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
- Read result.crossingIndexes. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.
Scan adjacent values and return index j exactly when value[j-1] is above threshold and value[j] is at or below it.1
| Input field | Meaning and representation | Accepted input |
|---|---|---|
| values | values. | List of finite numbers; bounded by the operation |
| threshold | threshold. | Finite number |
| Output field | Interpretation |
|---|---|
| result | Object containing the named outputs below. |
| result.crossingIndexes | The crossing indexes list in the ordering and representation described above. |
{
"input": {
"values": [
0,
1,
2,
1,
0
],
"threshold": 1
},
"output": {
"result": {
"crossingIndexes": [
3
]
}
}
}Limitations and assumptions
- A departure from a sample already equal to the threshold is excluded. The tool uses exact comparisons and supplies neither crossing timestamps nor behavior between samples.
- Every declared top-level field is required and unexpected fields are rejected. Numeric inputs must be finite; ordinary text fields are bounded to 8,192 UTF-16 code units, with tighter operation-specific limits where stated.
- Ordinary string lists have at most 128 entries of at most 128 code units each; numeric lists and matrices have separate bounded size checks. Nonfinite results and excessively large serialized outputs are rejected.
- Indexes are zero-based and spans have an exclusive end unless explicitly stated otherwise. A valid false, null or empty-list result is distinct from malformed input.
Alternative or Complementary methods
Choose a sampling model before combining results. Earlier-sample hold, linear interpolation and index-only differences answer different questions; event cooldown, debounce and rolling limits also use different acceptance rules.
References
Similar or alternative tools
- Threshold Upcrossing Indexes
Find up crossings from strictly below to the threshold-or-beyond; equality plateaus do not repeatedly trigger.
- Consecutive Threshold Streaks
Tabulate sampled consecutive threshold streaks with explicit at-or-above versus strictly-below convention; no between-sample duration inference.