Re: mathlib

[Dirk Laurie <dirk.laurie@...>]

2014-04-06 17:02 GMT+02:00 Roberto Ierusalimschy <roberto@inf.puc-rio.br>:
>> [...] Of course, reasons are more important than mere votes [...]
>
> Well said. Reasons are *much* more important than mere votes for us.
> More exactly, reasons count, votes do not.

Apart from the statement "few people use them" that cannot
be checked since votes do not count, the main reasons for
removing sinh, cosh, tanh seem to be:

1. Those that want it removed don't use them.
2. Unlike sin, cos, tan, there is no asinh, acosh, atanh.
3. You don't learn about them already in high school.
4. You can always get them via mathx.
5. There are simple identities to express them in terms of exp.

The main reasons for not removing them seem to be:

1. Those that do not want it removed use them.
2. Well then, supply asinh, acosh, atanh too.
3. You do learn about them at university.
4. mathx won't compile under C89.
5. The simple identities are perilous in floating point and
the expertise to circumvent that is considerable.

At this stage, as has been pointed out, it becomes sensible
to compare gains with losses.

Gains seem to be:

1. A few dozen bytes fewer in the executable. (Under `make linux`,
the 5.2.2 executable size is 214708 vs 214894.

2. A few lines fewer in the documentation.

3. A warm feeling under the heart that creeping featurism is
being combated by removing some features.

Losses seem to be:

1. Some people will find their old programs breaking.

2. It will no longer be true that "This library is an interface to the
standard C math library." At mosy it will be an interface to some
selected functions of that library.

3. A depressing feeling that Lua is going in a direction that
is by design unsympathetic to those who know a little more
mathematics than they teach you at school.

I possess an 86-piece drill and socket set. To date I have
not yet used the 11mm socket, the 16 mm flat-bit wood
drill, most of the variously shaped grindstones, and quite
a few others. But I know that they are there. That's rather
how I feel about the current Lua standard libraries.