Proper rounding procedure

[mmomtchev]

Currently the rounding rules of all flight leagues are not 100% clear and igc-xc-score seems to deviate from what is the most common practice, that is, by order:

• Round each leg separately
• Sum the rounded legs
• Round the penalty
• Apply the penalty
• Apply the multiplier
• Round the score

[mmomtchev]

Why is rounding so complicated and so important?

Because, very frequently, the optimizer has to choose between placing a TP in such way that you get

• a leg of x.4 and y.4 km
  or
• a leg of x.5 and y.3 km

If you simply round the final result, these can appear equivalent when they are not. Optimizing the rounded score is yet another layer to the general optimization problem that is definitely not trivial and straightforward.

[hyperknot]

Mathematically I cannot imagine a situation where you'd like to round multiple small numbers before summing them. I'd just round everything at the very last step and keep floating point until that point.