I am trying to write this equation with latex:

enter image description here

this is the code I wrote:


\min \sum_{i=1}^{$\infty$} $u_j$ (L.B.H) - \sum_{i=1}^{N} \emph{$l_i$}.\emph{$b_i$}.\emph{$h_i$}


but I get this error:

! Missing $ inserted.
<inserted text> $

I don't know where is the missing $

  • Welcome to TeX.SX! You can have a look at our starter guide to familiarize yourself further with our format. – Seamus May 25 '16 at 11:08
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    @Mico Are you really sure? I'd say it's the empty line... – campa May 25 '16 at 11:14
  • @campa - Your're right. There are (at least) two errors: The first error is the blank line, which generates the "Missing $ inserted." error message. The second error, caused by the spurious $ symbols in the upper limit of summation, generates a different error message: "Missing { inserted"... – Mico May 25 '16 at 11:40

First of all, empty lines are not allowed in displayed math environments (like equation), remove those. Second, you are in math mode, so there is no need for $\infty$, \infty alone is correct. Finally, the \emph doesn't really do anything useful I think, I would remove them and the dollar signs.

\min \sum_{j=1}^{\infty} u_j (L.B.H) - \sum_{i=1}^{N} l_i.b_i.h_i

enter image description here

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    @Samuel Not my typo, that's copied from the question. But thanks, will fix. – Torbjørn T. May 25 '16 at 11:08
  • Using periods for multiplication is not usual in mathematics – egreg May 25 '16 at 11:15
  • @egreg I find it odd myself, and if it were me I'd use \cdot or nothing. – Torbjørn T. May 25 '16 at 11:22
  • @egreg It depends on what you are taught. During my secondary school period, my math teacher told the class to not use the x symbol for multiplication like primary school taught us, and instead to use a period. I switched to using * during college because that's what programmers use. – Nzall May 25 '16 at 12:13
  • @Nzall * looks awful I think. And periods are of course useless if you have decimal numbers and use a period there as well. – Torbjørn T. May 25 '16 at 12:19

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