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Old Mar 17, 2013, 01:41 AM   #1
swingerofbirch
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Pages, Math, and Rounding: Am I crazy or is there a bug?

I'm working on a school project for which I need to print out squares in very exact sizes. One needed to be 2 1/8" and one needed to be 2 3/8". I created a box for each in Pages, and since there's no way to enter fractions, I entered 2.125 for one and 2.375 for the other.

I happened to notice the first one rounded down to 2.12 and the second rounded up to 2.38. As these squares will be compared with each other, the way it rounded down for one and up for the other results in a difference of .01", which in this particular circumstance is significant. Unfortunately, there doesn't seem to be a way to tell Pages not to round up or down the size of a box.

When I learned math, we learned to always round up when faced with .5 increments. Am I wrong about this? It's late at night and my brain is a bit frazzled. I am looking for a pattern here, and I can't find it.

Here are two charts where I entered widths into the Inspector box for a box in Pages. The next column shows what Pages rounded the number to. And then the next box shows whether it went up or down. I don't see the pattern, but I'm probably missing something.

Or is there a bug?

Thanks!

Edit: I just tried these in the Calculator app (not the widget), where you can set the number of decimal places, and it always and reliably rounds up when faced with .5.
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Last edited by swingerofbirch; Mar 17, 2013 at 01:46 AM.
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Old Mar 17, 2013, 11:54 AM   #2
FoxFifth
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Quote:
Originally Posted by swingerofbirch View Post
... When I learned math, we learned to always round up when faced with .5 increments. Am I wrong about this? It's late at night and my brain is a bit frazzled. I am looking for a pattern here, and I can't find it. ...
I am an old person and at one time in my life was an accountant. The rounding rule that we followed was to round .5 towards the even number so 2.125 would round to 2.12 and 2.375 would round to 2.38. This supposedly was more accurate in that it resulted in sometime rounding up and sometimes down when .5 was involved rather than always rounding in the same direction and thereby introducing a bias in that direction. This method of rounding is discussed in the following: http://en.wikipedia.org/wiki/Roundin...d_half_to_even
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Old Mar 17, 2013, 07:38 PM   #3
swingerofbirch
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Originally Posted by FoxFifth View Post
I am an old person and at one time in my life was an accountant. The rounding rule that we followed was to round .5 towards the even number so 2.125 would round to 2.12 and 2.375 would round to 2.38. This supposedly was more accurate in that it resulted in sometime rounding up and sometimes down when .5 was involved rather than always rounding in the same direction and thereby introducing a bias in that direction. This method of rounding is discussed in the following: http://en.wikipedia.org/wiki/Roundin...d_half_to_even
Thank you for the explanation. That does seem to apply in the two examples I gave, but if you look at the chart I made, it seems to be more random than that. It's a bit perplexing. Thank you for reading and responding! The Wikipedia article was an interesting read. Reminds me of the movie Office Space where they created a computer virus to take advantage of a company's rounding procedure for financial gain.
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Old Mar 17, 2013, 07:57 PM   #4
sahnert
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Quote:
Originally Posted by swingerofbirch View Post
I'm working on a school project for which I need to print out squares in very exact sizes. One needed to be 2 1/8" and one needed to be 2 3/8". I created a box for each in Pages, and since there's no way to enter fractions, I entered 2.125 for one and 2.375 for the other.
Not sure about the rounding calculation, but if you are just trying to print the boxes at a specific size, you can use the rulers built in to Pages. I zoomed in to 300% to view the measurements precisely and made the boxes the exact widths you describe.

Hope is helps!


EDIT: oops, I see now you said squares and I did rectangles. Same thing applies though...
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Old Mar 17, 2013, 08:09 PM   #5
swingerofbirch
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Originally Posted by sahnert View Post
Not sure about the rounding calculation, but if you are just trying to print the boxes at a specific size, you can use the rulers built in to Pages. I zoomed in to 300% to view the measurements precisely and made the boxes the exact widths you describe.

Hope is helps!


EDIT: oops, I see now you said squares and I did rectangles. Same thing applies though...
Thanks very much! Don't know why I didn't think of trying that first.
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Old Mar 19, 2013, 02:53 PM   #6
jdechko
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Most dialog boxes aren't designed to handle thousandths of an inch, so they do the sensible thing (to them) and round the number. Have you tried actually printing the page and measuring the boxes?
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