Prime Test

**Quick** · January 16th 2007, 01:00 PM

I have a question for you guys.

I've attached an excel document with "Quick's Prime Test"

The question is, how often (excluding 2, 3, and 5) does it mess up?

If you can't read excel then I'll put tell you how it works...

**ThePerfectHacker** · January 16th 2007, 01:11 PM

Originally Posted by Quick

If you can't read excel then I'll put tell you how it works...

I cannot read it.

First, you should call it,
"Quick's Primality Algorithm" it sounds way cooler.

**Quick** · January 16th 2007, 01:26 PM

Originally Posted by ThePerfectHacker

I cannot read it.

First, you should call it,
"Quick's Primality Algorithm" it sounds way cooler.

Alright

Anyway "Quick's Primality Algorithm" works in 6 steps ( $n$ is the # being tested).

1. is $n\div 11$ a whole #? (if yes, it's not prime. If no, go on)

2. is $n\div 5$ a whole #? (if yes, it's not prime. If no, go on)

3. is $(n-1)\div 4$ a whole #? (if yes, go to step 5. If no, go to step 4)

4. is $(n-3)\div 4$ a whole #? (if yes, go to step 5. If no, it's not prime)

5. is $(n-1)\div 6$ a whole #? (if yes, it's prime. If no, go to step 6)

6. is $(n-5)\div 6$ a whole #? (if yes, it's prime. If no, it's not prime)

**Quick** · January 16th 2007, 02:14 PM

I'm actually more interested to see if there is even a way to find out the ratio between actual primes and pseudoprimes for this test...

**Jhevon** · July 7th 2007, 10:36 AM

Originally Posted by Quick

I'm actually more interested to see if there is even a way to find out the ratio between actual primes and pseudoprimes for this test...

How did you develop this algorithm? as for your current signature, "Quick's Property: $\frac{n^2}{n-1}\div n=\frac{n^2}{n-1}-n$ " what's that about? does it also have to do with primes?

**ThePerfectHacker** · July 7th 2007, 05:38 PM

Originally Posted by Jhevon

How did you develop this algorithm? as for your current signature, "Quick's Property: $\frac{n^2}{n-1}\div n=\frac{n^2}{n-1}-n$ " what's that about? does it also have to do with primes?

I am the one who told him it does not work for 0 nor 1.

No, the signature is his own invention that he finds amusing that division gives the same result as subtraction.

**janvdl** · July 7th 2007, 10:27 PM

Originally Posted by ThePerfectHacker

I am the one who told him it does not work for 0 nor 1.

He should just put a semi-colon between the 0 and the 1. It looks like 0,1 at the moment.

**CaptainBlack** · July 8th 2007, 05:29 AM

Originally Posted by janvdl

He should just put a semi-colon between the 0 and the 1. It looks like 0,1 at the moment.

The comma is the correct punctuation mark (not only that but in the US and
UK at least "." is the decimal point not "," so to our minds there is no
confusion.

RonL

**janvdl** · July 8th 2007, 05:33 AM

Originally Posted by CaptainBlack

The comma is the correct punctuation mark (not only that but in the US and
UK at least "." is the decimal point not "," so to our minds there is no
confusion.

RonL

But South Africa adopted the British system many years ago.
And we use commas...

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