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Posted to github@datafusion.apache.org by "jonasdedden (via GitHub)" <gi...@apache.org> on 2026/09/24 11:25:54 UTC
[I] trunc(x) on a column turns -0.0 into 0.0 [datafusion]
jonasdedden opened a new issue, #25702:
URL: https://github.com/apache/datafusion/issues/25702
`trunc(x)` drops the sign of `-0.0`, but only when it runs on a column. On a scalar, and for `trunc(x, 0)`, the sign is kept.
```sql
SELECT trunc(column1), trunc(column1, 0) FROM (VALUES (CAST(-0.0 AS DOUBLE)));
-- got: 0.0, -0.0
-- expected: -0.0, -0.0
```
The column code path returns `0.0` for either zero:
```rust
if x == 0_f64 { 0_f64 } else { x.trunc() }
```
`-0.0 == 0.0` is true, so `-0.0` becomes `0.0`. `f64::trunc` already keeps the sign, so plain `x.trunc()` would be enough.
Seen through Lance (pylance 12.0.0): `trunc(x, 0)` on a `-0.0` column returns `-0.0`. This line is the same on `main` and in 55.1.0. I found no existing issue or PR for it.
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Re: [I] trunc(x) on a column turns -0.0 into 0.0 [datafusion]
Posted by "1fanwang (via GitHub)" <gi...@apache.org>.
1fanwang commented on issue #25702:
URL: https://github.com/apache/datafusion/issues/25702#issuecomment-5827398309
take
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Re: [I] trunc(x) on a column turns -0.0 into 0.0 [datafusion]
Posted by "adriangb (via GitHub)" <gi...@apache.org>.
adriangb closed issue #25702: trunc(x) on a column turns -0.0 into 0.0
URL: https://github.com/apache/datafusion/issues/25702
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