FA-61049 / Bond day-count conventions / Member archive

NL/365 no-leap day count: the year fraction uses actual days while the day count excludes leap days · case 04

The two returned values disagree whenever a leap day falls inside the span.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

Inputs start and end [y,m,d]. If end < start return "end before start". Days are actual days minus the number of 29 February dates lying in (start, end]. Return [days, days/365 rounded to 9 decimals].

Why this case matters

Bond accrual and pricing systems depend on exact day-count arithmetic; a single-day error changes settlement cash.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression fraction numerator 1	`[1022, 2.802739726]`	`[1022, 2.8]`	Failed

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