fix: correct scientific notation formatting for %e/%E#908
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Motivation:
DecimalFormat.format used ceil(log10(x))-1 to compute the exponent, which
produced wrong results for exact powers of 10 (e.g., 1.0, 100.0) and
numbers less than 1. Additionally, the .replace("E","E+") call in
Format.scala corrupted negative exponents to "E+-".
For example, std.format("%e", 0.001) produced "10.000000e+-04" instead
of the correct "1.000000e-03".
Modification:
- Use floor(log10(x)) for correct exponent calculation in DecimalFormat.
- Include explicit sign (+/-) directly in the exponent fragment.
- Remove all .replace("E","E+") calls in Format.scala.
Result:
Scientific notation now matches go-jsonnet output for all normal numbers.
Verified: 0.001→1.000000e-03, 1.0→1.000000e+00, 100.0→1.000000e+02,
910→9.100000e+02.
Contributor
Author
|
I tested it with code in python, this pr is right. |
stephenamar-db
approved these changes
Jun 9, 2026
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Summary
DecimalFormat.formatexponent calculation:ceil(log10(x))-1→floor(log10(x)).replace("E","E+")corrupting negative exponents to"E+-"std.format("%e", 0.001)previously produced"10.000000e+-04", now correctly produces"1.000000e-03"Verification against reference implementations
*go-jsonnet has a known bug for 1000.0; our output matches Python (the spec reference) and jrsonnet.
Test plan
DecimalFormatTestsexpected values to include explicit signformat_scientific_notation.jsonnet