On Sun, 23 Jan 2011, Steven Watanabe wrote:
AMDG
Over the last year I've been (slowly) updating Boost.Random to match the new standard. Unfortunately I just hit a problem that I don't have a good solution for. In the standard, the geometric_distribution is defined as $p(i) = p(1-p)^{i}$, with i >= 0. In the current Boost.Random code it is $p(i) = (1-p) p^{i-1}$, with i >= 1. The definition in the standard makes more sense, but I don't want to introduce a breaking change. I can see two options here:
* Leave the implementation alone and put a big warning in the documentation saying that the behavior doesn't match the standard. * Since I'm also moving things into namespace boost::random, I can use the new definition and leave a version with the old behavior in namespace boost instead of having a using declaration. I'd still have to add a warning that boost::geometric_distribution isn't the same as boost::random::geometric_distribution.
Neither one is particularly appealing. Any thoughts? Better ideas?
I noticed that discrepancy between Boost.Random and usual definitions of geometric_distribution as well, but forgot to report it; I would prefer to have the standard definition rather than the current one. I support your second option, as long as people don't have both "using namespace boost;" and "using namespace boost::random;" in the same code. Since you state that you will be moving things around, you are likely to be deprecating the versions in boost::, and so the change in geometric_distribution would fit into the same category. -- Jeremiah Willcock