Error in binary arithmetics


by megaflop
Tags: arithmetics, binary, error
megaflop
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#1
Dec17-12, 02:03 PM
P: 10
Hello everyone !
I got a problem, I can't figure out why when I compute [itex]A+B[/itex] and [itex]2\times (\frac{A}{2}+\frac{B}{2})[/itex] the result is sometimes different.
Can anyone explain why the results of the two operations are different ?

Edit : A and B are coded in binary of course and we compute a binary addition.
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jim hardy
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#2
Dec17-12, 02:12 PM
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Are you using integer or floating point ?

My guess is former , and one of the numerators is an odd number.
megaflop
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#3
Dec17-12, 02:14 PM
P: 10
Integers I forgot to mention sorry.

jim hardy
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#4
Dec17-12, 02:24 PM
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Error in binary arithmetics


Well there ya go.

Got Basic?

FOR I = 1 , 10 , 1
PRINT I, INT( I/2)
NEXT I
END
megaflop
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#5
Dec17-12, 02:32 PM
P: 10
Quote Quote by jim hardy View Post
Well there ya go.

Got Basic?

FOR I = 1 , 10 , 1
PRINT I, INT( I/2)
NEXT I
END
I see thank you :) .
uart
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#6
Dec17-12, 09:38 PM
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Quote Quote by megaflop View Post
Integers I forgot to mention sorry.
Does only "misbehave" if you're using one or more odd integers?


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