What you suggest is to effectively maintain two versions of MPIR, one
version 2.1 the other 3. We did consider such an option, but it is
much harder than it seems, and we simply don't have sufficiently many
contributors to manage that, whereas there seems to be a lot of
interest in contributing to a BSD licensed library. Another individual
I asked about this said they thought it was a great idea and that one
of the main things that puts them off currently is the LGPL. They
can't contribute to a BSD licensed library in the short term, but
perhaps in a year or so they may.

So that is 7 potential regular and talented developers for a BSD
licensed library. We probably have 7 contributors for an LGPL license
if we include the GMP regular contributors in that count. But I think
we will easily exceed this number with a BSD license. If I turn out to
be wrong about that, we will have to do something like what you
suggest.

Bill.

On 16 April 2010 08:36, Sergey Bochkanov <[email protected]> wrote:
> Hello, Mpir-devel.
>
> I've read discussion about future of LGPL-licensed MPIR, and about new
> BSD-licensed  library.  May  be there is much more simpler solution to
> the LGPL 3 issue than making new library.
>
> As  far  as  I  can  see, all updates may be divided into two distinct
> groups:
> * bugfixes
> * improved  algorithms  -  but  with  the same functionality as in the
>  previous version of the library. There  were  no  NEW  functions  in
>  several previous releases.
>
> Bugfixes  are  relatively  easy  to implement in LGPL 2. But what with
> these new algorithms?
>
> The  only  difference  from  old ones is performance, I think. But how
> large  is this difference? In the mpn layer, I think, it can't be VERY
> large.  10% faster - very likely. 50% faster - possible. 300% faster -
> unlikely.
>
> I  know  that performance is like Holy Grail for bignum community (and
> for  linear  algebra  community  too). But it isn't the only important
> factor. Other important factors are:
> * functionality (fast, but without functions you need = useless)
> * license questions (if you are the only library with  LGPL 2.1  code,
>  you will have your share of users even with moderate performance)
> * ease  of  use  (if  I were to choose between 1 hour of my time spent
>  studying unfamiliar build environment and 3  hours of CPU time  lost
>  with  slower  library, I'd choose slower library - I can read a book
>  while CPU is glowing hot).
> * support  by  community.  There are a lot of bignum libraries around,
>  but  they aren't supported anymore, and no one want to use them just
>  because of that.
>
> So, I propose to:
> * separate MPIR sources into two groups - 2.1-licensed  and
>  3.0-licensed, but hold them together within one distribution.
> * implement every algorithm in 2.1-licensed code. You still have a lot
>  of fast 2.1-licensed code.
> * use 3.0 licensed code when you have it, but it should be treated  as
>  addition to 2.1 codebase, but not as the main implementation.
> * build MPIR either as LGPL 2.1 or 3.0 licensed library. In the  first
>  case  only  2.1  code  is  used,  in  the  second  case build system
>  overrides 2.1-licensed algorithms with 3.0 licensed files.
>
> In such case you can have:
> * good enough implementations for those who needs LGPL 2.1
> * state-of-the-art implementations for those who happy with LGPL 3
> * one library instead of "New MPIR" and "Old-but-still-supported-MPIR"
> * easy support - you don't have to support two branches anymore
>
> What do you think about such idea?
>
> --
> With best regards,
>  Sergey                          mailto:[email protected]
>
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