Question

I am working on ps1:#1. I have been banging me head against the wall for some time now trying to figure it out. It seems that the simplest way to find a prime number is to take your test (n%n-1) and check for remainder == 0. This way you can differentiate between prime and not prime numbers. However, I cannot seem to get things to work right in python, and now I feel that this may not even be an accurate way to calculate prime numbers (deterministically).

I would greatly appreciate some pointers in the right direction on how to get this assignment to work. Thanks in advance.

Answer 1

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Answer 2

yes, I am

Answer 3

go to chat

Answer 4

looking around, not seeing a chat icon. are we already in chat?

Answer 5

it should be at the bottom of the page.

Answer 6

http://codepad.org/irXZYVQJ

Answer 7

The way I approached calculating if a number is prime was to make sure that you cannot represent the number as a combination of prime factors rather than going through all the numbers smaller than itself. eg. 36 = 2^2 * 3^2

-So if we start with list primes [2,3], the next obvious number to check if its a prime is 5 (first odd number)
- I check if 5 is divisible by 2 or 3, if not then it is a prime and I add to list of primes = [2,3,5]
- I then check the next odd number 7, which is also prime as it is not divisible by 2, 3 or 5, so primes = [2,3,5,7]
- Then I check 9, which is divisible by 3, I skip and go to 11 and so on.

This way you go through a much smaller list of numbers each time
http://codepad.org/G52Va8xf

Answer 8

Thanks for your response! I actually figured it out for the most part. Went a slightly different route and was getting some strange print outputs regardless of correct prime values. I will take a look at yours and compare the two. Thanks again.