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Math Help - Sigma or sum with index or indicies

  1. #1
    Super Member Bernhard's Avatar
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    Sigma or sum with index or indicies

    I know how to create a sigma sign for a sum - use the large operator \sum

    But how do you show an index, say i running from, say, 1 to n

    Further, how do you neatly create two or more indices

    Would appreciate any help in this matter

    Peter
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  2. #2
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    Re: Sigma or sum with index or indicies

    Quote Originally Posted by Bernhard View Post
    I know how to create a sigma sign for a sum - use the large operator \sum
    But how do you show an index, say i running from, say, 1 to n
    Further, how do you neatly create two or more indices
    [TEX]\sum\limits_{k = 2}^{10} {\ln (k)} [/TEX] gives \sum\limits_{k = 2}^{10} {\ln (k)}~.
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  3. #3
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    Re: Sigma or sum with index or indicies

    The formula mode (inline or display) determined whether operator indices are placed as regular sub/superscripts or directly below/above the operator. You can change this behavior using \limits and \nolimits between an operator and an index.

    Concerning two or more indices (I assume something like 0 ≤ i ≤ m and 0 < j < n), you can either write them in one line or use the following example from The LaTeX Companion, 2nd edition (8-3-5, p. 488):

    \sum_{\substack{0 \le i \le m \\ 0 < j < n}} P(i, j).

    There is also an example
    Code:
    \sum_{\begin{subarray}{l}  i \in \Lambda   \\
                               0 \le i \le m   \\
                               0 < j < n
          \end{subarray}}  P(i, j)
    but it does not work on MHF.
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  4. #4
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    Re: Sigma or sum with index or indicies

    Quote Originally Posted by Bernhard View Post
    I know how to create a sigma sign for a sum - use the large operator \sum

    But how do you show an index, say i running from, say, 1 to n

    Further, how do you neatly create two or more indices

    Would appreciate any help in this matter

    Peter
    Use \sum_{lower limit}^{upper limit} for \displaystyle \sum_{\textrm{lower limit}}^{\textrm{upper limit}}.
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