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  4. It's Primes as far as the eye can see!

It's Primes as far as the eye can see!

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  • N newton saber

    All odd numbers are prime, right? Let me check. Yep, all odd numbers are prime. Makes it a lot easier to count by the primes. Also, are there more odd numbers or even numbers? I know the answer, but it's a puzzle for you.

    I Offline
    I Offline
    Ian Shlasko
    wrote on last edited by
    #6

    newton.saber wrote:

    Also, are there more odd numbers or even numbers? I know the answer, but it's a puzzle for you.

    I dunno, let's find out... You start naming odd numbers, and I'll start naming even numbers... Whoever can name more of them wins! :laugh: By the way, is Infinity odd or even? I mean, it's a sideways 8, and 8 is even... But since it's sideways, that's a little odd, right? It's also kind of a car, except they spell it oddly, so maybe the original spelling is even... My head hurts...

    Proud to have finally moved to the A-Ark. Which one are you in?
    Author of the Guardians Saga (Sci-Fi/Fantasy novels)

    D 1 Reply Last reply
    0
    • N newton saber

      All odd numbers are prime, right? Let me check. Yep, all odd numbers are prime. Makes it a lot easier to count by the primes. Also, are there more odd numbers or even numbers? I know the answer, but it's a puzzle for you.

      OriginalGriffO Offline
      OriginalGriffO Offline
      OriginalGriff
      wrote on last edited by
      #7

      newton.saber wrote:

      it's a puzzle for you.

      Not really: there are an infinite quantity of each. The way we define "more", "less", and "equal" for infinite quantities is as follows. For two collections A and B (say A are the even numbers and B are the odd numbers) we say that If you can associate every item in A with a unique item in B, and vice versa, then A and B are the same size. If you can associate every item in A with a unique item in B, but not vice versa, then B is bigger than A. If you can associate every item in B with a unique item in A, but not vice versa, then A is bigger than B. In this case you can associate every even number n with the odd number n+1, and you can associate every odd number m with the even number m−1 (assuming 0 is even) so therefore there are just as many odd numbers as even numbers.

      Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

      "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
      "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt

      N 1 Reply Last reply
      0
      • I Ian Shlasko

        newton.saber wrote:

        Also, are there more odd numbers or even numbers? I know the answer, but it's a puzzle for you.

        I dunno, let's find out... You start naming odd numbers, and I'll start naming even numbers... Whoever can name more of them wins! :laugh: By the way, is Infinity odd or even? I mean, it's a sideways 8, and 8 is even... But since it's sideways, that's a little odd, right? It's also kind of a car, except they spell it oddly, so maybe the original spelling is even... My head hurts...

        Proud to have finally moved to the A-Ark. Which one are you in?
        Author of the Guardians Saga (Sci-Fi/Fantasy novels)

        D Offline
        D Offline
        den2k88
        wrote on last edited by
        #8

        Quote:

        By the way, is Infinity odd or even? I mean, it's a sideways 8, and 8 is even... But since it's sideways, that's a little odd, right?

        Please, stop! You're hurting me! :-D

        1 Reply Last reply
        0
        • N newton saber

          All odd numbers are prime, right? Let me check. Yep, all odd numbers are prime. Makes it a lot easier to count by the primes. Also, are there more odd numbers or even numbers? I know the answer, but it's a puzzle for you.

          P Offline
          P Offline
          PIEBALDconsult
          wrote on last edited by
          #9

          newton.saber wrote:

          All odd numbers are prime, right?

          No, primes aren't just any odd number.

          N 1 Reply Last reply
          0
          • Z ZurdoDev

            OriginalGriff wrote:

            call me old fashioned, but in my day, 9, 15 and 21 were divisible by 3

            Ya, but that's also back when Pluto was a planet. We live in a very different place now. This user submitted this in QA, got closed, and resubmitted it in QA. I told him to post as a tip but apparently he didn't realize some explanation should be added. Or, the important part, THAT IT SHOULD WORK! :laugh:

            There are only 10 types of people in the world, those who understand binary and those who don't.

            D Offline
            D Offline
            DaveAuld
            wrote on last edited by
            #10

            RyanDev wrote:

            but that's also back when Pluto was a planet

            There was a thing on the telly recently that stated it had been voted back in as a planet.

            Dave Find Me On:Web|Facebook|Twitter|LinkedIn Folding Stats: Team CodeProject

            Z P N 3 Replies Last reply
            0
            • D DaveAuld

              RyanDev wrote:

              but that's also back when Pluto was a planet

              There was a thing on the telly recently that stated it had been voted back in as a planet.

              Dave Find Me On:Web|Facebook|Twitter|LinkedIn Folding Stats: Team CodeProject

              Z Offline
              Z Offline
              ZurdoDev
              wrote on last edited by
              #11

              True fans never gave up hope. :thumbsup::thumbsup:

              There are only 10 types of people in the world, those who understand binary and those who don't.

              1 Reply Last reply
              0
              • OriginalGriffO OriginalGriff

                This is the whole of a would-be Tip submitted today:

                public class Class1
                {
                static void Main(string[] args)
                {
                Console.WriteLine("Enter a Number");
                int num = int.Parse(Console.ReadLine());
                for (int i = 1; i <=num ; i++)
                {
                if(i==2)
                Console.WriteLine(2);

                            if (i % 2 != 0)
                            {
                                Console.WriteLine(i);
                            }
                        }
                
                     }
                }
                

                No text, no explanation - the author (I can only assume he works for Mindfire, it's about their level) clearly felt that it spoke for itself. And boy, does it ever! This, ladies-n-gentlemen, is a Prime Number generator according to the author. So...I tried it... According to this code, the prime numbers under 26 are:

                1
                2
                3
                5
                7
                9
                11
                13
                15
                17
                19
                21
                23
                25

                Now, call me old fashioned, but in my day, 9, 15 and 21 were divisible by 3, and both 15 and 25 were divisible by 5... So which is wrong? The Code? Or the Laws of Mathematics? Only the author can tell... :laugh:

                Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

                P Offline
                P Offline
                PIEBALDconsult
                wrote on last edited by
                #12

                At least he used the % operator rather than implementing his own function.

                OriginalGriffO I 2 Replies Last reply
                0
                • P PIEBALDconsult

                  At least he used the % operator rather than implementing his own function.

                  OriginalGriffO Offline
                  OriginalGriffO Offline
                  OriginalGriff
                  wrote on last edited by
                  #13

                  I suspect luck was involved.

                  Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

                  "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
                  "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt

                  1 Reply Last reply
                  0
                  • P PIEBALDconsult

                    At least he used the % operator rather than implementing his own function.

                    I Offline
                    I Offline
                    Ian Shlasko
                    wrote on last edited by
                    #14

                    Yeah, it could have been worse...

                    public static bool SeeIfNumberIsOdd(int i)
                    {
                    for (int n = i; n > 0; n--)
                    {
                    if (n==1)
                    return true;
                    else if (n==2)
                    return false;
                    }
                    return true;
                    }

                    That felt dirty to write... Ok, I probably could have made it a LITTLE worse... Maybe O(n^2), but that might be gratuitous.

                    Proud to have finally moved to the A-Ark. Which one are you in?
                    Author of the Guardians Saga (Sci-Fi/Fantasy novels)

                    P 1 Reply Last reply
                    0
                    • I Ian Shlasko

                      Yeah, it could have been worse...

                      public static bool SeeIfNumberIsOdd(int i)
                      {
                      for (int n = i; n > 0; n--)
                      {
                      if (n==1)
                      return true;
                      else if (n==2)
                      return false;
                      }
                      return true;
                      }

                      That felt dirty to write... Ok, I probably could have made it a LITTLE worse... Maybe O(n^2), but that might be gratuitous.

                      Proud to have finally moved to the A-Ark. Which one are you in?
                      Author of the Guardians Saga (Sci-Fi/Fantasy novels)

                      P Offline
                      P Offline
                      PIEBALDconsult
                      wrote on last edited by
                      #15

                      See the mod function in here: http://www.codeproject.com/script/Articles/ArticleVersion.aspx?aid=830657[^]

                      I 1 Reply Last reply
                      0
                      • P PIEBALDconsult

                        See the mod function in here: http://www.codeproject.com/script/Articles/ArticleVersion.aspx?aid=830657[^]

                        I Offline
                        I Offline
                        Ian Shlasko
                        wrote on last edited by
                        #16

                        Bah, I can do better than that!

                        //TODO: Remove all comments before publishing. Real programmers don't need comments!
                        public function SuperMod(int n, int o) // o is a great variable, because it looks like a zero
                        {
                        int p = o; //Shorter variable names make the code run faster!
                        loopy: //Labels make me feel young again!
                        while (p < n) p += o;
                        if (p < n) goto loopy; //Just in case the compiler makes a mistake
                        int answer = p - n;
                        return answer;
                        }

                        Ok, I think that's about as bad as I can make it, and though I didn't test it at all (Honestly, I think the compiler would come to life and slit my throat for even trying to execute this monstrosity), that should technically give the right answer... Unless 'o' is negative or zero, but validating parameters is so 20th century...

                        Proud to have finally moved to the A-Ark. Which one are you in?
                        Author of the Guardians Saga (Sci-Fi/Fantasy novels)

                        P B 2 Replies Last reply
                        0
                        • I Ian Shlasko

                          Bah, I can do better than that!

                          //TODO: Remove all comments before publishing. Real programmers don't need comments!
                          public function SuperMod(int n, int o) // o is a great variable, because it looks like a zero
                          {
                          int p = o; //Shorter variable names make the code run faster!
                          loopy: //Labels make me feel young again!
                          while (p < n) p += o;
                          if (p < n) goto loopy; //Just in case the compiler makes a mistake
                          int answer = p - n;
                          return answer;
                          }

                          Ok, I think that's about as bad as I can make it, and though I didn't test it at all (Honestly, I think the compiler would come to life and slit my throat for even trying to execute this monstrosity), that should technically give the right answer... Unless 'o' is negative or zero, but validating parameters is so 20th century...

                          Proud to have finally moved to the A-Ark. Which one are you in?
                          Author of the Guardians Saga (Sci-Fi/Fantasy novels)

                          P Offline
                          P Offline
                          PIEBALDconsult
                          wrote on last edited by
                          #17

                          Ian Shlasko wrote:

                          give the right an answer

                          FTFY

                          I 1 Reply Last reply
                          0
                          • P PIEBALDconsult

                            newton.saber wrote:

                            All odd numbers are prime, right?

                            No, primes aren't just any odd number.

                            N Offline
                            N Offline
                            newton saber
                            wrote on last edited by
                            #18

                            PIEBALDconsult wrote:

                            No, primes aren't just any odd number.

                            Of course they are. It's ridiculous to think that they aren't.

                            1 Reply Last reply
                            0
                            • OriginalGriffO OriginalGriff

                              newton.saber wrote:

                              it's a puzzle for you.

                              Not really: there are an infinite quantity of each. The way we define "more", "less", and "equal" for infinite quantities is as follows. For two collections A and B (say A are the even numbers and B are the odd numbers) we say that If you can associate every item in A with a unique item in B, and vice versa, then A and B are the same size. If you can associate every item in A with a unique item in B, but not vice versa, then B is bigger than A. If you can associate every item in B with a unique item in A, but not vice versa, then A is bigger than B. In this case you can associate every even number n with the odd number n+1, and you can associate every odd number m with the even number m−1 (assuming 0 is even) so therefore there are just as many odd numbers as even numbers.

                              Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

                              N Offline
                              N Offline
                              newton saber
                              wrote on last edited by
                              #19

                              This is terribly incorrect, because I stopped counting on an odd number, so there are more odd numbers than even. Thank you for your input. :D

                              P 1 Reply Last reply
                              0
                              • OriginalGriffO OriginalGriff

                                This is the whole of a would-be Tip submitted today:

                                public class Class1
                                {
                                static void Main(string[] args)
                                {
                                Console.WriteLine("Enter a Number");
                                int num = int.Parse(Console.ReadLine());
                                for (int i = 1; i <=num ; i++)
                                {
                                if(i==2)
                                Console.WriteLine(2);

                                            if (i % 2 != 0)
                                            {
                                                Console.WriteLine(i);
                                            }
                                        }
                                
                                     }
                                }
                                

                                No text, no explanation - the author (I can only assume he works for Mindfire, it's about their level) clearly felt that it spoke for itself. And boy, does it ever! This, ladies-n-gentlemen, is a Prime Number generator according to the author. So...I tried it... According to this code, the prime numbers under 26 are:

                                1
                                2
                                3
                                5
                                7
                                9
                                11
                                13
                                15
                                17
                                19
                                21
                                23
                                25

                                Now, call me old fashioned, but in my day, 9, 15 and 21 were divisible by 3, and both 15 and 25 were divisible by 5... So which is wrong? The Code? Or the Laws of Mathematics? Only the author can tell... :laugh:

                                Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

                                P Offline
                                P Offline
                                PIEBALDconsult
                                wrote on last edited by
                                #20

                                http://www.codeproject.com/Lounge.aspx?msg=85311#xx85311xx[^] http://www.codeproject.com/search.aspx?q=prime+number+error&categoryid=f1_1159_[^]

                                1 Reply Last reply
                                0
                                • OriginalGriffO OriginalGriff

                                  This is the whole of a would-be Tip submitted today:

                                  public class Class1
                                  {
                                  static void Main(string[] args)
                                  {
                                  Console.WriteLine("Enter a Number");
                                  int num = int.Parse(Console.ReadLine());
                                  for (int i = 1; i <=num ; i++)
                                  {
                                  if(i==2)
                                  Console.WriteLine(2);

                                              if (i % 2 != 0)
                                              {
                                                  Console.WriteLine(i);
                                              }
                                          }
                                  
                                       }
                                  }
                                  

                                  No text, no explanation - the author (I can only assume he works for Mindfire, it's about their level) clearly felt that it spoke for itself. And boy, does it ever! This, ladies-n-gentlemen, is a Prime Number generator according to the author. So...I tried it... According to this code, the prime numbers under 26 are:

                                  1
                                  2
                                  3
                                  5
                                  7
                                  9
                                  11
                                  13
                                  15
                                  17
                                  19
                                  21
                                  23
                                  25

                                  Now, call me old fashioned, but in my day, 9, 15 and 21 were divisible by 3, and both 15 and 25 were divisible by 5... So which is wrong? The Code? Or the Laws of Mathematics? Only the author can tell... :laugh:

                                  Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

                                  P Offline
                                  P Offline
                                  PhilLenoir
                                  wrote on last edited by
                                  #21

                                  That's odd!

                                  Life is like a s**t sandwich; the more bread you have, the less s**t you eat.

                                  1 Reply Last reply
                                  0
                                  • D DaveAuld

                                    RyanDev wrote:

                                    but that's also back when Pluto was a planet

                                    There was a thing on the telly recently that stated it had been voted back in as a planet.

                                    Dave Find Me On:Web|Facebook|Twitter|LinkedIn Folding Stats: Team CodeProject

                                    P Offline
                                    P Offline
                                    PhilLenoir
                                    wrote on last edited by
                                    #22

                                    That's democracy for you!

                                    Life is like a s**t sandwich; the more bread you have, the less s**t you eat.

                                    1 Reply Last reply
                                    0
                                    • P PIEBALDconsult

                                      Ian Shlasko wrote:

                                      give the right an answer

                                      FTFY

                                      I Offline
                                      I Offline
                                      Ian Shlasko
                                      wrote on last edited by
                                      #23

                                      Heh, yeah, you're right... It needs to be n+o-p... But hey, what's the point of testing when you're trying to write the worst code possible? (Still haven't tested... I was going to, but the compiler pulled a knife on me and said some very non-KSS things would happen if I tried)

                                      Proud to have finally moved to the A-Ark. Which one are you in?
                                      Author of the Guardians Saga (Sci-Fi/Fantasy novels)

                                      1 Reply Last reply
                                      0
                                      • I Ian Shlasko

                                        Bah, I can do better than that!

                                        //TODO: Remove all comments before publishing. Real programmers don't need comments!
                                        public function SuperMod(int n, int o) // o is a great variable, because it looks like a zero
                                        {
                                        int p = o; //Shorter variable names make the code run faster!
                                        loopy: //Labels make me feel young again!
                                        while (p < n) p += o;
                                        if (p < n) goto loopy; //Just in case the compiler makes a mistake
                                        int answer = p - n;
                                        return answer;
                                        }

                                        Ok, I think that's about as bad as I can make it, and though I didn't test it at all (Honestly, I think the compiler would come to life and slit my throat for even trying to execute this monstrosity), that should technically give the right answer... Unless 'o' is negative or zero, but validating parameters is so 20th century...

                                        Proud to have finally moved to the A-Ark. Which one are you in?
                                        Author of the Guardians Saga (Sci-Fi/Fantasy novels)

                                        B Offline
                                        B Offline
                                        Bert Mitton
                                        wrote on last edited by
                                        #24

                                        Cut and pasted ! :laugh:

                                        I 1 Reply Last reply
                                        0
                                        • B Bert Mitton

                                          Cut and pasted ! :laugh:

                                          I Offline
                                          I Offline
                                          Ian Shlasko
                                          wrote on last edited by
                                          #25

                                          Ok, but if you're gonna use that code, make sure to either fix the bug, or... uh... only test with (4,2).

                                          Proud to have finally moved to the A-Ark. Which one are you in?
                                          Author of the Guardians Saga (Sci-Fi/Fantasy novels)

                                          B 1 Reply Last reply
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