Weird formatting behavior

[TheIronBorn]

this code:

let x = f16::from_f32(std::f32::consts::PI);
println!("{:.1e}", x);
println!("{:.1e}", f32::from(x));

produces this

3.140625e0
3.1e0

f16::debug just uses fmt(self.to_f32(), f) so I don't know what might be causing this

[VoidStarKat]

This is due to PI not being equal to 3.14 when converted to a 16-bit float. It's actually: 3.0996094. Loss of precision can be surprisingly nasty with 16-bit floats.

[TheIronBorn]

3.09 should still print 3.1 when given the single decimal formatting

[VoidStarKat]

Oh I see, I read this all backwards. Yeah that is odd

…

On Thu, Mar 13, 2025, 11:24 p.m. TheIronBorn ***@***.***> wrote: 3.09 should still print 3.1 when given the single decimal formatting — Reply to this email directly, view it on GitHub <#112 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB7JFRYMNIPUQWQ66ER7IVL2UJDWBAVCNFSM6AAAAABY7RGR42VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDOMRTGMYTCMJQG4> . You are receiving this because you modified the open/close state.Message ID: ***@***.***> [image: TheIronBorn]*TheIronBorn* left a comment (VoidStarKat/half-rs#112) <#112 (comment)> 3.09 should still print 3.1 when given the single decimal formatting — Reply to this email directly, view it on GitHub <#112 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB7JFRYMNIPUQWQ66ER7IVL2UJDWBAVCNFSM6AAAAABY7RGR42VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDOMRTGMYTCMJQG4> . You are receiving this because you modified the open/close state.Message ID: ***@***.***>