Re: re-writing algorithms in Guile

[Tim Meehan <btmeehan@gmail.com>]

Thanks all for the input - I think I have a better understanding of
derivative work. I think that I'll look for a paper on the algorithm and
work from there.

For the curious, the "hypothetical" code in question was from here
<https://codetobuy.com/downloads/brent-dekker-method-as-a-root-finding-method-of-any-equation/>
:
Since he posted it in "algorithmic" form, and I had no interest in
purchasing his code to run in Matlab (since Matlab likely has something
faster anyhow), I was puzzled about what I might be able to do with my pure
Scheme version.

On Tue, Jun 29, 2021 at 9:22 AM <tomas@tuxteam.de> wrote:

> On Tue, Jun 29, 2021 at 01:52:56PM +0000, Nate Rosenbloom wrote:
> >
> > > This reason is not stated in the Stack Exchange post, and I believe
> > > it’s inaccurate (although, I am not a lawyer either). I think the
> > > reason is that you are reading the original implementation to write
> > > your own, so you are some kind of a compiler, or translator (as for
> > > human spoken languages). As such, what you write is mostly the other
> > > person’s work, so you should not claim copyright about it.
> >
> > Sorry, I should have been more specific, the rewritten algorithm would
> not be the same, but it would be a derivative work and still covered by
> copyright of the original work.
>
> I think the legal concept of "derivative work" is far more complex than
> we'd all like. See [1] to get an idea.
>
> With the caveat that I'm not a lawyer (heh), I think the "red line" lies
> between those two extremes: (a) you read the original, understand the
> algorithm and write your program based on this understanding. Best if
> you forget details like variable naming, program structure, etc. Only
> the "pure" algorithm survives, and (b) you translate the program line
> by line (although that would be pretty hard between C and, say, idiomatic
> Scheme). (a) is almost certainly not a derivative work, while (b) would
> be, most probably.
>
> To make sure you can cleanly /prove/ you did (a), some do what is called
> a "clean room implementation". Fred looks at the original program and
> tells Gina "how it works", and Gina implements the new one.
>
> Cheers
>
> [1] https://copyleft.org/guide/comprehensive-gpl-guidech5.html
>
>  - t
>