alignment of symbols

Question

I tried to align the equation and have some text on the equal sign. But it turns out that the equal sign that has text over it is no longer aligned to previous one anymore (I believe it is the text "ccc" that is aligned). How do I fix the problem to let the equal sign aligned but not text over it?

\begin{equation}
\begin{split}
    a  &= b \\        
       &\overset{ccc}{=}d\\
       &= e\\
\end{split}
\end{equation}

Answer 1

You can use the mathtools package and the command \mathclap, which gives the text a width of 0, center aligned:

\usepackage{mathtools}
...
 & \overset{\mathclap{ccc}}{=}d\\
...