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Somebody please explain me the Miller Rabin Primality test

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
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It is a probabilistic test for determining primality belonging to the field of computational number theory.

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Yes, how to do it?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
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For once Wiki actually did a good job explaining something!!!!

```
Input: n > 3, an odd integer to be tested for primality;
Input: k, a parameter that determines the accuracy of the test
Output: composite if n is composite, otherwise probably prime
Go:
write n − 1 as 2^s·d with d odd by factoring powers of 2 from n − 1
WitnessLoop: repeat k times:
pick a random integer a in the range [2, n − 2]
x ← ad mod n
if x = 1 or x = n − 1 then do next WitnessLoop
repeat s − 1 times:
x ← x^2 mod n
if x = 1 then return composite
if x = n − 1 then do next WitnessLoop
return composite
return probably prime
```

Can not do any better than that except to do some filling in.

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And what does this method actually rely on?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

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**bobbym****Administrator**- From: Bumpkinland
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A whole lot of number theory and a thing called a strong pseudo prime.

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Mainly fermat's little theorem?

And what ensures it is strong?

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

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**bobbym****Administrator**- From: Bumpkinland
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Offhand I never remember that definition of them but I could look it up.

More to the point is the test itself and the fact that it is a non deterministic test.

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Not the definition but I am asking what gives them a **HIGH ** probability of being prime?

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

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**bobbym****Administrator**- From: Bumpkinland
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That I do not remember. I am sorry.

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Thats okay.

Once I know that a number is probably prime, how do I make sure?

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'But our love is like the wind. I can't see it but I can feel it.' -A Walk to remember

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**bobbym****Administrator**- From: Bumpkinland
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Three of your countryman developed the AKS algorithm which is deterministic and fast. Or you can use Miller Rabin.

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Three of my countrymen? Who are they?

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'But our love is like the wind. I can't see it but I can feel it.' -A Walk to remember

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**bobbym****Administrator**- From: Bumpkinland
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Manindra Agrawal, Neeraj Kayal, and Nitin Saxena

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I did not know them.

I shall google it

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'But our love is like the wind. I can't see it but I can feel it.' -A Walk to remember

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**bobbym****Administrator**- From: Bumpkinland
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Are they all three Indians?

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The names sound so, but how does it matter?

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'But our love is like the wind. I can't see it but I can feel it.' -A Walk to remember

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**bobbym****Administrator**- From: Bumpkinland
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It matters in the sense that I like to differ from the rest of my kind.

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Would that change the method essentially?

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

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**bobbym****Administrator**- From: Bumpkinland
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Change the method? I am not understanding you.

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Me neither

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'But our love is like the wind. I can't see it but I can feel it.' -A Walk to remember

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
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The AKS proves a number is prime while the Miller Rabin tells the probability it is prime.

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**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
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Or we could just wait for someone to solve the P vs NP problem.

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Who will bell the cat?

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'But our love is like the wind. I can't see it but I can feel it.' -A Walk to remember

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**bobbym****Administrator**- From: Bumpkinland
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Did you have anymore questions about MIller Rabin?

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