Elementary Functions

Elementary Functions

[N.G. Timmons]

Hi,

I was looking through the source for sin/cos/exp etc. and noticed that a 
lot of the comments don't actually say what/why things are being done.
There also exists a union type called "mynumber" which is used to access 
the high and low bits of a 64-bit floating point number.

I would like to comment the elementary functions with:
     - What algorithm is being used
     - Why is it being used
     - Any caveats on unusual operations so future changes can be made 
safely
     - Actual testing information (the current statistics given at the 
top of some functions doesn't say how they were tested). This is to 
allow for verification and comparison if future changes are made.

I would like to rename 'mynumber' and a few other variables to 
meaningful names so that the source code can be followed with greater 
ease.

Would the community be open to me making these changes?

Thanks,
Nick Timmons

Re: Elementary Functions

[Carlos O'Donell]

On Mon, Jan 13, 2020 at 10:09 AM N.G. Timmons <ngt26@cam.ac.uk> wrote:
>
> Hi,
>
> I was looking through the source for sin/cos/exp etc. and noticed that a
> lot of the comments don't actually say what/why things are being done.
> There also exists a union type called "mynumber" which is used to access
> the high and low bits of a 64-bit floating point number.
>
> I would like to comment the elementary functions with:
>      - What algorithm is being used
>      - Why is it being used
>      - Any caveats on unusual operations so future changes can be made
> safely
>      - Actual testing information (the current statistics given at the
> top of some functions doesn't say how they were tested). This is to
> allow for verification and comparison if future changes are made.
>
> I would like to rename 'mynumber' and a few other variables to
> meaningful names so that the source code can be followed with greater
> ease.
>
> Would the community be open to me making these changes?

I think such changes would be great.

The various elementary math functions are part of glibc and we don't
import that code from anywhere anymore
(https://sourceware.org/glibc/wiki/SharedSourceFiles).

Joseph Myers does a lot of review of these functions and given your
email address I expect you might know him? :-)

Please post to libc-alpha@sourceware.org so core developers can see your post.

Usually libc-help is for help of one kind or another, and your
question is more directly related to developers.

Thanks!

Cheers,
Carlos.