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Thread: Unending Loop Issue? Can't find it.

  1. #1
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    Question Unending Loop Issue? Can't find it.

    Although I think this is an issue with my loops structure/conditions this could also be an issue with how Java does arithmetic. I'm sure this is probably simple but I can't find it right now.
    The polynomial object is composed of an array of size 100 which stores the coefficients of a polynomial in index locations corresponding to the power of each respective term. The purpose of this code is to create a new polynomial object which is the result of multiplying two polynomials.
    I'm pretty sure that the loop is not ending but I'm not sure why. The initial S.o.ps of i+j values are what I expect but then they go into enormous negative numbers and I have no idea why.
      public Polynomial mult(Polynomial p)
                        throws ExponentOutOfRangeException
      {
          Polynomial multiPolynomial = new Polynomial();
     
     
          //Start testcode
          System.out.print("this polynomial ");
          this.displayPolynomial();
          System.out.print("p polynomial ");
          p.displayPolynomial();
          //End testcode
     
     
          for(int i = 0; i < 99; i++)
          {
              for(int j = 0; j < 99; i++)
              {
                if((i+j) < MAX)
                {
                    multiPolynomial.polyArr[i + j] = multiPolynomial.polyArr[i + j] + (this.polyArr[i] * p.polyArr[j]);
                }
              }
          }
       // Multiplies polynomial p to this polynomial without modifying this
       // polynomial and returns the result.
       // Precondition: None.
       // Postcondition: The returned polynomial is the product of this 
       // and p.  Both this and p are unchanged.
       // Throws: ExponentOutOfRangeException if exponent is out of range.
          return multiPolynomial;
      }
    By the way,
    Last edited by helloworld922; March 4th, 2011 at 07:01 PM.


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    Default Re: Unending Loop Issue? Can't find it.

    Thanks to whoever fixed the way the code displays here. I was looking up the necessary tags just now. Anyone see the problem? Maybe I should include more code...

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    Default Re: Unending Loop Issue? Can't find it.

    for(int j = 0; j < 99; i++)
    You're incrementing i in the j loop, not j

  4. The Following User Says Thank You to helloworld922 For This Useful Post:

    javapenguin (March 4th, 2011)

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    Default Re: Unending Loop Issue? Can't find it.

    You seem to be incrementing i twice.

    Perhaps you should change it to j++;

    As it is, i is being incremented twice and j is stuck at 0.

    Musta posted at same time as helloworld922.

    Oh well.

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    Default Re: Unending Loop Issue? Can't find it.

    Omigosh, how embarrassing! I looked at the problem is sooo many ways and I missed that simple item. I guess that's why you ask other people to look at code. Thanks guys!

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