help need proper equation!
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Thread: help need proper equation!

  1. #1
    Join Date
    Jan 2009
    Posts
    6

    Exclamation help need proper equation!

    For this program I have to obtain the variance. The variance is obtained by subtracting the calcAverage from each value in testvals, squaring the values obtained, adding them, and dividing by the number of elements in testvals. Basically the last line of code I need help because I can't figure out how to do all the math with one formula. This is the formula I need help with:

    Code:
    variance = ((testvals[i] - (testvals, MAXELS)));
    I know thats not right obviously. So any help would be greatly appreciated
    Heres what I have so far:

    Code:
    #include <iostream>
    #include <iomanip>
    #include <cmath>
    
    using namespace std;
      
      const int MAXELS=14;
      float calcAverage(int [MAXELS]); //function prototype
      float variance(int [MAXELS]); //function prototype
    int main()
    {
      int testvals[MAXELS] = {89, 95, 72, 83, 99, 54, 86, 75, 92, 73, 79, 75, 82, 73};
      cout << "The average of these numbers is: " <<calcAverage(testvals) <<endl;
      cout << "The variance of these number is: " <<variance(testvals) <<endl;
    system("pause");
      return 0;
    }
    //find the average value
    float calcAverage(int testvals[MAXELS])
    {
        int i;
        float calcAverage, total=0;
        for(i=0; i < MAXELS; i++)
       {
         total=total+testvals[i];
       }
         calcAverage=total/MAXELS;
           return calcAverage;
    }
    
    //find the variance
    float variance(int testvals[MAXELS])
    {
          int i;
          float calcAverage, sqd, variance=0;
          for (i=0; i < MAXELS; i++)
      {   
          variance = ((testvals[i] - (testvals, MAXELS)));
      }
      return variance;
    }

    Please help me out! I would really appreciate it
    Last edited by Marc G; February 3rd, 2009 at 04:07 AM. Reason: Added code tags

  2. #2
    Join Date
    Jun 2005
    Posts
    315

    Re: help need proper equation!

    I can't figure out how to do all the math with one formula
    Is doing the calculation in multiple steps not an option?

  3. #3
    Join Date
    Jan 2009
    Posts
    6

    Re: help need proper equation!

    Actually it is an option but I just don't know how to do it at all.

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