It's complicated. :-) There is a nice picture of the "best" choice for different ranges of sizes of numbers to be multiplied at http://gmplib.org/devel/log.i7.

It's complicated. :-) There is a nice picture of the "best" choice for different ranges of sizes of numbers to be multiplied at http://gmplib.org/devel/log.i7.1024.png http://gmplib.org/devel/log.i7.1024.png More context and explanation can be found at: http://gmplib.org/devel/ http://gmplib.org/devel/