# "erroneous nesting of equation structures" , using \boxed, can't identify the problem

I want to create a frame around a piece of math notation, I'm using the \boxed{} command to do that:

\boxed{ \begin{align*} &p = \text{Intervallverhältnis von 1 Cent} \\ &2 = \text{Intervallverhältnis der reinen Oktave} \\ \\ &p^{1200} = 2 \rightarrow p = \sqrt[1200]{2} \end{align*} }


It looks exactly how I want it to look like in the compiled pdf, but overleaf.com outputs the following error message: Package amsmath error: erroneous nesting of equation structures. Where is the problem and why does it still work? Are there other or better ways of achieving a black frame around a piece of math notation (or any kind of text) easily? I'm very much a beginner. Thanks in advance :)

• Welcome! You should never use $$ in LaTeX. Your problem can be solved with the empheq package. Commented Mar 8, 2020 at 13:15 • (Off topic.) Rather than using two double backslashes to insert a blank line, the option \\[<dimen>] can give more control. But, when using amsmath, be sure to not insert a space between the \\  and the option. Commented Mar 8, 2020 at 18:32 ## 1 Answer You should never use $$ in LaTeX. Ever.

Anyway, it makes no sense to nest align* inside \boxed, because align* wants to be at the outer level (not even inside equation). You can look at the empheq package for more tricks, but in your case it suffices to do

\begin{equation*}
\boxed{
\begin{aligned}
&p = \text{Intervallverhältnis von 1 Cent} \\
&2 = \text{Intervallverhältnis der reinen Oktave} \\ \\
&p^{1200} = 2 \rightarrow p = \sqrt[1200]{2}
\end{aligned}
}
\end{equation*}