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Add read-only planning and repository-changing development skills so BCQuality knowledge can guide features, bug fixes, refactors, upgrades, and maintenance before the existing AL review gate runs. Track Microsoft Learn ingestion and add development and BCApps-shaped guidance evaluation fixtures. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 638b66d2-9f06-4f60-8781-808709e1485c
30 lines
1.4 KiB
Markdown
30 lines
1.4 KiB
Markdown
---
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bc-version: [all]
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domain: data-modeling
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keywords: [round, rounding, direction, precision, negative-decimal, amount]
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technologies: [al]
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countries: [w1]
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application-area: [all]
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---
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# `Round` direction symbols follow magnitude, not mathematical ordering
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## Description
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AL's `Round(Number, Precision, Direction)` uses `'>'` to round away from zero and `'<'` to round toward zero. For a negative value this reverses mathematical ordering: `Round(-1234.56789, 0.001, '<')` returns `-1234.567`, while direction `'>'` returns `-1234.568`. Code that treats the symbols as mathematical ceiling and floor produces sign-dependent amount errors, commonly on credit documents and negative adjustments.
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## Best Practice
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Choose the direction from the business meaning: `'>'` increases absolute magnitude and `'<'` decreases absolute magnitude for both positive and negative values. Include positive and negative cases whenever a directed rounding rule is tested.
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See sample: `round-direction-symbols-use-magnitude.good.al`.
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## Anti Pattern
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Using `'<'` as a mathematical floor or `'>'` as a mathematical ceiling. The result looks correct for positive amounts but moves in the opposite mathematical direction for negative amounts.
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See sample: `round-direction-symbols-use-magnitude.bad.al`.
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## Reference
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[Use the Round function](https://learn.microsoft.com/en-us/training/modules/use-document-standards-business-central/4a-use-round-function)
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