Dmitriy Gorbel wrote
I dislike the names. I don't really understand what the first 2 types have to do with fixed-point math, other than maybe as an implementation detail or degenerate fixed-point type (0 fractional bits). I add cardinal and integral types to the proposal because
Michael Marcin-3 wrote this types required by C++1y proposal. I agree, this types quite illogical. Maybe, this types proposed for supporting big integers, but I think for big integers better use Boost.Multiprecision library.
It's easy to implement integral types based on fractional, using template aliases, for example: template
using cardinal = nonnegative<Range, 0>; template using integral = negatable<Range, 0>; What community think about this? Should library support integral fixed point types?
The implementation of fixed
Neal Becker wrote
Thank you. The last time we discussed this topic, the issue was not one of notation, but of different semantics that were desired by different end users of a fixedpoint type.
I think there were several areas of disagreement - but perhaps primary was whether arithmetic operations would produce different types or the same types, and how to handle arithmetic between mixed types. For example, does multiplication of 2 8-bit quantities promote to 16 bits or not.
My preference is/was that no implicit conversion was ever performed and that it always had to be explicit. This is partly because the primary consumer for this technology (I think) is those working on FPGA or ASIC hardware - and they should always be aware of any such conversions. Best way - conversion policy, when user can choose between implicitly/explicitly conversion. I will try to implement both variants.
No, this is not solved by implicit/explicit conversion, but using closed arithmetic. That is fixed<8>* fixed<8>-> fixed<8> The C++1y proposal uses open arithmetic and fixed<8>* fixed<8>-> fixed<16> Using closed arithmetic the user must explicitly convert to the desired result fixed<8> a; fixed<16> b = fixed<16>(a) * fixed<16>(a); Best, Vicente -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-FixedPoint-Choose-notation-tp464626... Sent from the Boost - Dev mailing list archive at Nabble.com.