FA-81078 / Music interval and transposition theory / Member archive

Interval-class vector of a pitch-class set: interval class stored one slot high · case 03

A semitone is recorded in the ic2 slot and a major third in the ic4 slot.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Input a list of integers, reduced mod 12 and deduplicated. For each unordered pair count its interval class min(d, 12-d) in 1..6. Return the six counts [ic1..ic6]; non-integer input returns None.

Why this case matters

Interval vectors drive set-class similarity measures and Z-relation detection.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
oracle 0	`[0, 1, 0, 0, 0, 0]`	`[1, 0, 0, 0, 0, 0]`	Failed

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