Kevin wrote:
there is no such library in the boost tree yet. I'm working on one and since this library hasn't been proposed for review yet, I'd suggest to factor this dependency out as a template parameter in your source if that is possible in a convenient way.
It is easy for me to make the high precision data type a member of coordinate_traits that defaults to same type as is used to store the result of an area computation, but can be specialized to any user defined data type. That would factor the dependency out, as you say. Perhaps I should provide meta-function for this instead of traits.... I took a look at your linked source and there were quite a few files there. Which ones pertain to large integer types. mp_int.h appeared to be the class that provides high precision integer arithmetic, providing infinite/variable precision arithmetic on an array of digit values, with support for negative numbers. Can your digit_type be 64 bit unsigned integer? If so you have pretty much the ideal variable precision integer. --snip-- private: digit_type* digits_; size_type used_, capacity_; int sign_; }; --end snip-- Why not simply use std::vector<digit_type, Allocator> instead of managing your own array? mp_int is actually overkill for my immediate problem, but would certainly do the job and allow me to make a general solution. It looks like something we need in a place like boost. I managed to solve my immediate problem by distributing division and recovering the lost precision due to truncation with modulus operations. I had to use 64 bit unsigned integers with associated sign stored in a separate integer to perform hastily hacked up 65 bit signed arithmetic. I used this to compute the product of deltas between signed 32 bit integers and work with those values to eventually compute the intersection of two line segments in a way that is robust to overflow and truncates the result minimally and predictably. When do you think your mp_int library will be ready for review? I have to provide a solution internally within a month or so and plan to submit the geometry library to boost once completed, probably around end of year. Luke _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost