Re: [boost] Big Int

From: Christoph Ludwig (cludwig_at_[hidden])
Date: 2005-03-05 15:13:06

On Sat, Mar 05, 2005 at 07:34:22PM +0100, Richard Peters wrote:
> Oh, there are a few ways in which you can perform computations with the
> expression templates, but that was not what I meant. My point was: If you
> specify the result of operators + and - to be big_integer, then expression
> templates cannot be made to work, because then those operators return types
> other than big_integer. User code may depend on the specification that those
> operators do return big_integers. Therefore, any implementation satisfying
> the requirements of the C++ standard library proposal will miss the possible
> speedincrease gained by the use of expression templates.

Can you point me to any data about the speedup of bigint operations due
to ET? How complex need the expressions to be and what is the bitlength
threshold so that programs profit from ET? (I am aware that ET can have a huge
effect on the speed of matrix operations, but there you typically need to
allocate / copy / deallocate much more data if you have temporary objects.)

Does anyone know what speedup one can expect if the move-semantic proposal is
applied to bigint types? (Say, for simple expressions like x = y + z and 
x = y * z.)

Regards

Christoph
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