FA-81083 / Music interval and transposition theory / Member archive

Interval-class vector of a pitch-class set: negative pitch numbers reflected instead of reduced · case 03

A set containing -1 is analysed as if it contained 1, so [-1,0,4] gets the wrong vector.

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 4	`[1, 0, 0, 0, 0, 0]`	`[0, 0, 1, 0, 0, 0]`	Failed

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