Reference library4 entries

Category: Python

Decimal, float, and rounding behavior in Python for sig figs.

Sig Figs in Python: round(), format(), and Decimal — Which One Follows ASTM E29?

Python's round() and format() use half-even ties, matching ASTM E29 for exact ties, but binary floats can break decimal rounding. Decimal.quantize() is the reliable…

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How to Round to Significant Figures in Python Using the decimal Module

Use Decimal.quantize with an exponent derived from the adjusted exponent to round to n significant figures, choosing ROUND_HALF_EVEN for standards-aligned ties.

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Why Python’s round() Uses Banker’s Rounding: A Precision Reference

Python's round() implements banker's rounding (round half to even) to reduce cumulative bias in statistical operations. This article explains the rationale, standards, and practical…

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Rounding to Significant Figures in Python: Precision, Pitfalls, and Best Practices

Learn how to round numbers to a specified number of significant figures in Python, including the pitfalls of binary floating-point, banker's rounding, and standards-based…

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