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Subject: [boost] [fixed_point] Request for interest in a binary fixed point library
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2012-04-04 17:33:15


Hi,

the recent discussion on the MultiplePrecission Arithmetic library has
show that some people has its ow fixed point library.

Is there an interest in a Boost library having as base
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3352.html?

I have started a prototype
http://svn.boost.org/svn/boost/sandbox/fixed_point (there is no doc yet
but the basic goal is quite close to the N3352 C++ proposal). This
prototype should allow you to play a little bit with.

If yes, what would you like to be changed, added or improved in n3352?
Next follows some design decisions that IMO need to be decided before hand.

* Should integers and reals be represented by separated classes?
* Should signed and unsigned be represented by separated classes?
* Should the library use a specific representation for signed numbers
(separated sign, 2-complement? Let the user choose?
* Should the library provide arbitrary range and resolution and allocators?
* Should the library be open to overflow and rounding or just implement
some of the possible policies? and in this case which ones?
* Should fixed_point be convertible to/from integer/float/double?
* Could the result of an arithmetic operation have more range and
resolution than his arguments?
* Is there a need for a specific I/O?
* is there a need for radix other than 2 (binary)?
* Should the library implement the basic functions, or should it
imperatively implement the C++11 math functions? Could a first version
just forward to the c++11 math functions?
* Should the library support just one of the know ways to name a
fixed-point, a U(a,b), nQm, ...? Provide some ways to move from one to
another?
* Could expect the same/better performances respect to hand written code?
* What should be the size used by a fixed_point instance? _fast? _least?
Should the user be able to decide which approach is better for his needs?
* Which should be the namespace? boost? boost/fixed_point?
boost/binary_fixed_point? boost/bfp?
...
* others you can think of.

Please, replay if you are interested, have some experience in the
domain, good ideas, ..

Best regards,
Vicente


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