I'm going through some of these from an old homework assignment (i'm in a structural materials class) and I have no problem with how to solve and get your miller index with reciprocals and simplifying fractions etc., but I don't know how they are initially deciding which corner of the cube to use for the origin. I've looked at a lot of different criteria, as well as tons of websites, and it seems flat out random to me. even online I can't find any info at all about how they decide, and it affects the +/- of the answer, so it's a bit of a problem...
any ideas?
thanks
-Jon