On Fri, Jul 13, 2012 at 9:51 AM, Craig Ringer
<craig(at)postnewspapers(dot)com(dot)au> wrote:
> ... but it feels like there must be a smarter way.
Well, may be kind of (h1 - h2), (h2 - h1) and derivatives will make sense?
--
Sergey Konoplev
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