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Error while calculating sum of n terms of a exponential series to n terms:

This is a discussion on Error while calculating sum of n terms of a exponential series to n terms: within the C Programming forums, part of the General Programming Boards category; Following is my program for calculating the sum of exponential series upto n terms: e = 1/0! + 1/1! + ...

  1. #1
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    Error while calculating sum of n terms of a exponential series to n terms:

    Following is my program for calculating the sum of exponential series upto n terms:

    e = 1/0! + 1/1! + 1/2! + 1/3! + 1/4! + 1/5!+....1/n!

    Code:
    #include<stdio.h>
    int main()
    {
      int n,i,p=1;
      float sum=1.0,fact=1.0;
      printf("enter the number of terms");
      scanf("the number of terms are %d",&n);
      for(i=1;i<=n;i++)
      {
                       while(p<=i)
                       {
                       fact*=p;
                       p++;
                       }
      sum+=(1.0/fact);
      }
      printf("the sum is %f",sum);
      system("pause");
      return 0;
    }
    While executing the code in dev-C++, the program stops executing and goes into an infinite loop after entering 'n'. Kindly help.

  2. #2
    ATH0 quzah's Avatar
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    You never reset the value of p, did you mean to?


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    It is not needed, is it? Everythime the next factorial is computed the variable fact alreaddy has the value of factorial of the earlier number. I am still getting the same problem, my program, even though it is running fine, doesn't proceed after entering the value of n.


    Quote Originally Posted by quzah View Post
    You never reset the value of p, did you mean to?


    Quzah.

  4. #4
    and the hat of wrongness Salem's Avatar
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    > printf("enter the number of terms");
    > scanf("the number of terms are %d",&n);
    Perhaps you should just have
    scanf("%d",&n);

    Otherwise, you have to type in
    the number of terms are 7
    quzah likes this.
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  5. #5
    Registered User camel-man's Avatar
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    Otherwise, you have to type in
    the number of terms are 7
    Salem, would that even be legal thing to do in C?

  6. #6
    and the hat of wrongness Salem's Avatar
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    > Salem, would that even be legal thing to do in C?
    Try it

    I mean of course, RTFM
    A directive is one of the following:

    A sequence of white-space characters (space, tab, newline, etc.; see isspace(3)). This directive matches any amount of white space, including
    none, in the input.

    An ordinary character (i.e., one other than white space or '%'). This character must exactly match the next character of input.

    A conversion specification, which commences with a '%' (percent) character. A sequence of characters from the input is converted according to
    this specification, and the result is placed in the corresponding pointer argument. If the next item of input does not match the conversion
    specification, the conversion fails — this is a matching failure.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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  7. #7
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    Thank youu so much guys! Couldn't spot the obvious

  8. #8
    Algorithm Dissector iMalc's Avatar
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    Calculate the factorial iteratively; you only need one loop.
    If the last factorial calculated was 4! then just multiply that previous value by 5 and behold you now have 5!
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  9. #9
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    Code:
    float sum=1.0,fact=1.0;
    Your sum should be equal to 0 not 1, cause you are not multiplying sum, you are adding.

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    Thanks everyone. @Stevan - actually the first term of my series is 1 which is not calculated while coding, so I am writing sum as 1 initially.

    Quote Originally Posted by Stevan View Post
    Code:
    float sum=1.0,fact=1.0;
    Your sum should be equal to 0 not 1, cause you are not multiplying sum, you are adding.

  11. #11
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    @abhishekcoder, which term, 1/0! ?

  12. #12
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    Yes.

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