FA-61932 / Currency rounding and FX conversion / Member archive

Legacy pairs use a derived direct cross rate instead of triangulating · case 02

Mark to franc conversions disagree with the triangulated reference amount.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

solve(amount, frm, to): stipulated legacy-currency triangulation. Fixed rates are units per 1 EUR (DEM 1.95583, FRF 6.55957, ITL 1936.27, ESP 166.386, IEP 0.787564, NLG 2.20371, BEF 40.3399, PTE 200.482, ATS 13.7603, FIM 5.94573). Exponents: ITL, ESP, BEF, PTE 0; others and EUR 2. Legacy to legacy: divide by the source rate, round the EUR intermediate half-up to 3 decimals, multiply by the target rate, round half-up to the target exponent. Legacy to EUR: divide and round half-up to 2 decimals. EUR to legacy: multiply and round half-up to the target exponent. Same currency: round the amount half-up to its exponent. Inverse rates are never used. Unknown codes return 'ERR:currency'.

Why this case matters

Currency amounts must be rounded at the right stage and in the right unit, or ledgers, quotes and settlements drift by minor units.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression direct-cross-rate 1	`"426.76"`	`"426.75"`	Failed

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