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| author | yoshi~ <jreusch4@gmail.com> | 2025-01-02 17:21:20 +0100 |
|---|---|---|
| committer | Louis Pilfold <louis@lpil.uk> | 2025-01-03 20:44:56 +0000 |
| commit | 619935a6e79dce3262712838c4cb1c1b69f33132 (patch) | |
| tree | bab9c83c3dea2c09f7f0fff5bb6c314240438390 | |
| parent | f9aea4a694fff1bd54cc43c807635a579cf8af8d (diff) | |
| download | gleam_stdlib-619935a6e79dce3262712838c4cb1c1b69f33132.tar.gz gleam_stdlib-619935a6e79dce3262712838c4cb1c1b69f33132.zip | |
improve precision
| -rw-r--r-- | CHANGELOG.md | 4 | ||||
| -rw-r--r-- | src/gleam/float.gleam | 12 | ||||
| -rw-r--r-- | test/gleam/float_test.gleam | 6 |
3 files changed, 20 insertions, 2 deletions
diff --git a/CHANGELOG.md b/CHANGELOG.md index dfc290d..60a4d6f 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -1,5 +1,9 @@ # Changelog +## Unreleased + +- Improved the precision of `float.to_precision`. + ## v0.51.0 - 2024-12-22 - `dynamic/decode` now has its own error type. diff --git a/src/gleam/float.gleam b/src/gleam/float.gleam index 34dba05..6aeeac7 100644 --- a/src/gleam/float.gleam +++ b/src/gleam/float.gleam @@ -261,8 +261,16 @@ pub fn truncate(x: Float) -> Int /// ``` /// pub fn to_precision(x: Float, precision: Int) -> Float { - let factor = do_power(10.0, do_to_float(-precision)) - do_to_float(round(x /. factor)) *. factor + case precision <= 0 { + True -> { + let factor = do_power(10.0, do_to_float(-precision)) + do_to_float(round(x /. factor)) *. factor + } + False -> { + let factor = do_power(10.0, do_to_float(precision)) + do_to_float(round(x *. factor)) /. factor + } + } } @external(erlang, "erlang", "float") diff --git a/test/gleam/float_test.gleam b/test/gleam/float_test.gleam index 1c8f96b..6503a6b 100644 --- a/test/gleam/float_test.gleam +++ b/test/gleam/float_test.gleam @@ -288,6 +288,12 @@ pub fn to_precision_test() { float.to_precision(435.3224, -0) |> should.equal(435.0) + + float.to_precision(184.20000000000002, 2) + |> should.equal(184.2) + + float.to_precision(12_345_678_912_345_678_912_345_678.0, -19) + |> should.equal(1_234_568.0e19) } pub fn min_test() { |