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Math Help - Sigma Function

  1. #1
    Senior Member sakonpure6's Avatar
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    Sigma Function

    Hi, I stumbled upon a question in my homework that mentioned sigma functions, and as I under stood, a sigma function is the sum of the factors of a number. Ex. f(5)= 5+1 (factors) = 6.

    I would like to know why this is so, Sigma function, does it have any other purpose ? And I thought functions are represented by equations? I hope my questions are clear because I feel like they are not >.<!

    Thank you in advance!

    -Cheers!
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  2. #2
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    Re: Sigma Function

    Quote Originally Posted by sakonpure6 View Post
    Hi, I stumbled upon a question in my homework that mentioned sigma functions, and as I under stood, a sigma function is the sum of the factors of a number. Ex. f(5)= 5+1 (factors) = 6.

    I would like to know why this is so, Sigma function, does it have any other purpose ? And I thought functions are represented by equations?
    I think that you are confused about this topic. Look at this webpage,
    Usually \sigma(5)=2 is the number of factors of five.
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  3. #3
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    Re: Sigma Function

    A "function" is any rule that to a specific "object" (typically a number but not necessarily), x, in a given set of objects, assigns a unique object, y. A different way of saying the same thing is "a set of ordered pairs of objects such that two different pairs cannot have the same first member. A function is NOT necessarily given by a formula. For example, the function defined by the formula y= x^2, with x any real number, is the set of ordered pairs, \{(x, x^2)| x\in R\}. Notice that the statement of the domain is an important part of the definition of the function. The set of ordered pairs, \{(x, x^2)| x\in R, x\ge 0\}, while having the same "formula" is a completely different function.
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