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PeterNewton

Sat Jun 12, 2010 12:08 pm


How to do Modular Arithmetic?

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What is it you are trying to achieve?
I'm trying to apply modular arithmetic to a certain variables. The purpose of the overall program is irrelevant.
If there is a function modar(x,y), x is my variable and y is the modulo, and I want the modar fucntion to output x mod y. I'm working in only modulo 2 if that simplifies anything.

What is the problem you are having?
I do not know the necessary function. Is there a preprogrammed one or would I have to make it? If it is not preprogrammed, how would I go about making it?

Please specify what version of Turing you are using
4.1.1


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TerranceN

Sat Jun 12, 2010 12:26 pm


RE:How to do Modular Arithmetic?

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I believe you want the mod command. Here is a small example on how to use it:

for i : 1..100
    put i..
    
    if (i mod 2 = 0) then
        put ": Even"
    else
        put ": Odd"
    end if
end for

Hope that helps.


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DtY

Sat Jun 12, 2010 3:56 pm


RE:How to do Modular Arithmetic?

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Since you're doing only mod 2, there's a faster way, 

function modar(x)
result x & 1
end modar

This is the equivalent to doing mod 10 arithmetic by only keeping the least significant digit.


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TheGuardian001

Sat Jun 12, 2010 4:01 pm


Re: How to do Modular Arithmetic?

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Turing uses and as the and operator. it doesn't have & or &&


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Tony

Sat Jun 12, 2010 7:10 pm


RE:How to do Modular Arithmetic?

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It does. They are both 
The and operator can also be applied to natural numbers. The result is the natural number that is the bit-wise and of the operands. See nat (natural number).



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DtY

Sat Jun 12, 2010 8:33 pm


RE:How to do Modular Arithmetic?

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It doesn't use &? I'm sure I used that last semester, weird

[edit] Actually, now that I think about it, I might not have, I remember having to look up how to do bit shifts too, was something awful like lhs and rhs or something.


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TheGuardian001

Sun Jun 13, 2010 12:45 am


Re: How to do Modular Arithmetic?

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Huh. Well what do you know, the and operator actually will do a bitwise and. Didn't know it was multi-functional.

And apparently both & and | are valid. Dunno why I thought they weren't...


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PeterNewton

Sun Jun 13, 2010 1:08 am


RE:How to do Modular Arithmetic?

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Thanks guys! The mod command works perfectly.