[Tex/LaTex] Why are minus signs not working in this equation

math-modesymbols

In the below equation I'm writing, 2 minus signs are not visible, why is that?

$\phi (s, \lambda) = C
\frac{
1 + \beta^2 − 2 \beta cos( \frac{2 \pi s}{\lambda} )
}{
\lambda^5 \exp(
\frac{
h c
}{
\lambda k B T
} − 1)
}
$

Best Answer

The problem is that the character you are using is the Unicode minus sign which is not recognized by LaTeX with your current settings; it is U+2212 MINUS (most probably a result from a copy-paste). Replace the symbols with the LaTeX minus signs and they will show.

I took the liberty of modifying a little your expression to produce a better result for an on-line expression (perhaps you could consider showing this as a displayed expression):

\documentclass{article}

\begin{document}

$\phi (s, \lambda) = C
\bigl( 1 + \beta^{2} - 2 \beta \cos(2 \pi s\lambda^{-1} ) \bigr) /
\bigl( \lambda^{5} \exp( \frac{ h c }{ \lambda k B T} - 1) \bigr)$

\end{document}

enter image description here

Notice that for the cosine function you should use \cos and not just cos.

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