[Info-vax] Floating Point, Machine Epsilon, Rust, Swift, Etc (was: Re: VMS Software Q1 '23 Update)

[Stephen Hoffman]

On 2023-02-01 13:17:06 +0000, Simon Clubley said:

> Something just occurred to me while writing this: does the latest 
> solution to everything :-) (ie: Rust) still allow you to directly 
> compare two floating point numbers ?


Rust crates:

https://docs.rs/float-cmp/latest/float_cmp/

https://docs.rs/efloat/latest/efloat/




Swift has a deliberately-obscurely-named equivalent to machine epsilon, 
as do some other languages.

https://en.wikipedia.org/wiki/Machine_epsilon

Unfortunately, stuff that's labeled "epsilon" is all too often not what 
you want to use.




And (more general, not specific to Rust) background on floating point:

https://randomascii.wordpress.com/category/floating-point/

https://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/ 
(part of a longer series)




The last OpenVMS port had a fairly long write-up on floating point, and 
the x86-64 probably has an update to same, as floating point is always 
"fun".



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