Possible bug when reading/writing large inexact numbers

Greg Rosenblatt

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Mar 7, 2021, 8:31:42 PM3/7/21

to Racket Users

Large inexact numbers may change values after a second round trip between read and write. I was expecting to reach a fixed point after the first round trip. Is this a bug?

Welcome to Racket v7.8 [cs].

> 4.57030e+53
4.5703e+53

> 4.5703e+53
4.5702999999999995e+53

Sorawee Porncharoenwase

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Mar 7, 2021, 8:42:33 PM3/7/21

to Greg Rosenblatt, Racket Users

This is already fixed. Racket 8.0 doesn't have this issue.

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Greg Rosenblatt

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Mar 7, 2021, 8:52:32 PM3/7/21

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Great, thanks. Out of curiosity, where in the reader was this bug originally? Can you point me to a diff?

Sam Tobin-Hochstadt

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Mar 7, 2021, 9:45:48 PM3/7/21

to Greg Rosenblatt, Racket Users

I believe it's https://github.com/racket/racket/commit/0561d71e60502fa857b0d169f64da723584d96d6

Sam

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