I have following equation:

enter image description here

I would like to use summation for the above equation. The index of summation is not an integer. Can I use the below equation to represent the above equation?

enter image description here

  • 4
    That is not really a LaTeX question, but rather about math notation.
    – daleif
    May 18 at 9:37
  • 4
    I’m voting to close this question because it's off-topic for TeX - LaTeX.
    – Werner
    May 18 at 22:07

As daleif said, not really a LaTeX question. But while we're here, my opinion:

The names a1.1, a1.2 etc are really unconvential for mathematical objects. Instead, consider putting the number in subscript, like $ a_{1.2} $. However, if they are mathematical objects, I would consider this perfectly fine notation.

Do note however you don't want too long of a subscript under your summation! For instance, here I would put $ I = \{a_{1.1}, a_{1.2}, a_{2}\} $ and then use $ \sum_{i\in I} $ in the equation.

  • 1
    You could even write $\sum_i$, and then say "where the sum ranges over ...".
    – Teepeemm
    May 18 at 21:55

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