Re: modulo question

[Scovetta Labs <security () scovettalabs com>]

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Martin,

I'm not sure if this is "correct", but as per:
        http://www.oremus.org/liturgy/etc/ktf/app/modulo.html
"A subtle point is that the remainder is always a positive number. So -7 divided
by 3 is -3, remainder 2 (rather than -2, remainder -1)."

So (-1)%2 should be 1, because 2*(-1) + 1 = -1
~   1%(-2) should be 1, because (-2)*(0) + 1 = 1

Of course, this could be totally wrong, if I'm missing something from the
fundamental definition of modulo arithmetic.

Also, python and C++ might bind the % and - operators at difference precedence
levels-- use parentheses to make sure.

- -Mike

martin wrote:
| Hello list,
|
| I have slightly academic question about modulo. I sent this message here
| because I thing there are many of gurus which working with modulo operator.
|
| I have tried in python and in C++ following:
|             python    C++
| 1%2      1           1
| -1%2     1          -1
| 1%-2    -1           1
| -1%-2   -1          -1
|
| What is right?
| Do you know some applications which using modulo with negative numbers?
| Have you some references to definition (mathematical def. and properties) of
| modulo?
|
| Thanks in advance,
| Martin

- --
Michael Scovetta
Scovetta Labs
www.scovettalabs.com
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