HP50g small tips and trick

[ttw]

Because the HP50 does not handle lists with zero or one element correctly, I had to come up with the following (unless I wanted to code separately for lists of size zero or one or two or more).

Sum List becomes << { 0 0 } Sum List} >> and Prod List becomes << {1 1} Prod List >>.

This works but it seems silly to have the built functions do some tests to produce incorrect behavior then I program tests to satisfy their tests.

In other cases, I needed (for a Monte Carlo choice from a list with varying weights) the running sum of an array. << OVER + >> STREAM. It probably doesn't work on empty lists.