Thread: problem with the divisor

I'm still work with my Prefect Number problem. But still have a little problem, the problem asks show all the divisor like this"1 + 2 + 3"
I tried the use "+" in the function, but the problem is i only get "1 + 2 + 3 +"
Q1: How to get rid of the last "+"?
Q2: I'm still work on the divisor, hope somebody can show good ideas for the divisor.
Thank you.
Here's my code:

PHP Code:

#include <stdio.h>
#include <math.h>

double i, j, k, b, N;
double prefect();
double list (double N);

int main (void)
{
  prefect();
  system("pause");
  return 0;
}

double prefect()
{
  k = 2;
  while(b <= 1000000000)
  {
    
      i=pow(2, k-1);
      j=pow(2, k);
      b=i*(j-1);
      k++;
      
      if (b <= 1000000000)
      {
          printf(" %.lf = %.lf * %.lf = ", b, i, j);
          List(N);
      }
  }

  return b;
}

//Comment: I'm still work on this divisor function, i really need help on this one//
double List (double N)
{
  double Div = N;

  while (--Div > 0){

    if ((N % Div) == 0 )
      printf ("%d +", Div);
  }
} 


with regard to printf ("%d +", Div);
make it be + %d and only print the number the first time.

Sorry, I still don't get it. How to make it work?

Prior to attempting to fix your list function (which has lots of problems), perhaps you should look at the output of your prefect function.

Code:

if (b <= 1000000000)
      {
          printf(" %.lf = %.lf * %.lf = ", b, i, j);
          List(N);
      }

What is this supposed to accomplish? I can't make anything out of it when I compile your code.

Originally posted by gabulldog
Prior to attempting to fix your list function (which has lots of problems), perhaps you should look at the output of your prefect function.

Code:

if (b <= 1000000000)
      {
          printf(" %.lf = %.lf * %.lf = ", b, i, j);
          List(N);
      }

What is this supposed to accomplish? I can't make anything out of it when I compile your code.

The problem is from the divisor"List" function. I'm still debugging.

I guess my point is you changed the output of your prefect function from the result of your calculations to an uninteligible output.

If you trying to get something like:
"6 = 1 + 2 + 3"

your code will not produce that no matter what you do to list.

That's why I recommend you fix prefect prior to working on list.

Your idea is really great, but the problem is it's too late, it's due this noon

It's never too late. You are almost there.

I recommend you go back to the original posting and use the printf call you had there. Change it to

Code:

 printf("\Prefect number: %.0f = ", b);

or whatever. Then look at your list function and follow Draco's advice.

20 minutes of work will fix this problem.

Originally posted by gabulldog
It's never too late. You are almost there.

I recommend you go back to the original posting and use the printf call you had there. Change it to

Code:

 printf("\Prefect number: %.0f = ", b);

or whatever. Then look at your list function and follow Draco's advice.

20 minutes of work will fix this problem.

Thanks a lot, Do you have any idea about the DIVISOR, the LIST function isn't really come from myself, I don't really understand it.

The question I have for you is what is list supposed to accomplish? If you want to get the multiple numbers, you already have a form of them in i, j and k. You just need to figure out how to print them in a readable fashion.

It won't ever work in its original form because N is already 0, so your first time through will skip the whole while loop.

Maybe you need to set N to something...

Originally posted by gabulldog
The question I have for you is what is list supposed to accomplish? If you want to get the multiple numbers, you already have a form of them in i, j and k. You just need to figure out how to print them in a readable fashion.

It won't ever work in its original form because N is already 0, so your first time through will skip the whole while loop.

Maybe you need to set N to something...

It asks to get a number of its factors including 1(except the number itself). I want to write a new function for the LIST

Sorry I couldn't get back to you in time. Good luck.

Thanks, Do you have any idea about the divisor,( not use modulo), That may help also.

What you need to do is figure out how to come up with the positive proper divisors. I've looked at the first three perfect numbers and have seen a pattern, which is the sum of the perfect number (b) = 2^0 + 2^1.....2^(k-1) + ((2^k)-1) + 2((2^k-1)...for k-1 times.

eg:

6 = 1 + 2+3 = (2^0) + (2^1) +( (2^2)-1)
28 = 1 + 2 + 4 + 7 + 14 = (2^0) + (2^1) +(2^2) +( (2^3)-1) +
2((2^3)-1)

Get the picture? Now all you need to do is to write a loop in your list function to reflect this pattern. And pass the perfect number into your function. Good luck!