piclist 2001\06\01\225753a >
www.piclist.com/techref/index.htm?key=brain+burp+rounding
BY : Kyle Stemen email (remove spam text)

One thing I don't like about the round to even method is that you lose
precision. Say you are measuring a value from 0 to 9. You have one sig
fig, and 10 different possiblities of what that number can be. Now lets
say that you had to do a calculation such as add .5. You would have to
round back to one digit. Here are the different possiblities with round
to even:
0.5 -> 0
1.5 -> 2
2.5 -> 2
3.5 -> 4
4.5 -> 4
5.5 -> 6
6.5 -> 6
7.5 -> 8
8.5 -> 8
9.5 -> 10

with always round up you have

0.5 -> 1
1.5 -> 2
2.5 -> 3
3.5 -> 4
4.5 -> 5
5.5 -> 6
6.5 -> 7
7.5 -> 8
8.5 -> 9
9.5 -> 10

With the round to even you can only have an even number so there are 6
possibilites of what it can be, and you started out with 10 so you have
lost precision. With always round up there are still 10 possibilies so
you have lost no precision, but they do not average out the same so you
have lost accuracy.

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