FA-58544 / Loan amortization schedules / Member archive

Adjustable rate reset with caps: first adjustment cap · case 04

The first reset is limited by the periodic cap instead of the initial cap.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

x = {'initial_bp', 'index_path': index at each reset, 'margin_bp', 'round_to', 'initial_cap_bp', 'periodic_cap_bp', 'lifetime_cap_bp' (above initial), 'floor_bp'}. At each reset the fully indexed rate index + margin is rounded half-up to a multiple of round_to, limited to within the cap of the previous note rate (initial cap at the first reset, periodic afterwards, both directions), then limited to [floor_bp, initial + lifetime cap]. Return the list of note rates.

Why this case matters

Amortization engines drive borrower statements, payoff quotes and investor remittances; a misplaced rounding step, boundary or ordering rule compounds across hundreds of periods.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression: first adjustment cap	`[550, 500, 450, 450]`	`[650, 550, 450, 450]`	Failed

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