[Tex/LaTex] Norm of “a” looks different from Norm of “b” in math mode

math-modetilde

I run into the following little problem in the LaTeX math mode:

$ \left \|\tilde{a}  \right \| + \left \| \tilde{b} \right \| $

when trying this in the Latex Equation Editor, it looks a bit weird: the norm around b is much bigger than the norm around a. Without the \tilde over b it acts normal. Is there a way to solve this easily or do i have to change letters? Or is there a smaller way to write \tilde{b} ?

Best Answer

Instead of using \left\|...\right\| which are extensible characters (meaning they grow vertically with the content height), use fixed height versions. You can call on larger versions with \big, \Big, \bigg, and \Bigg.

\documentclass{article}
\begin{document} 
$ \big \|\tilde{a}  \big \| + \big \| \tilde{b} \big \| $
\quad
$ \Big \|\tilde{a}  \Big \| + \Big \| \tilde{b} \Big \| $
\quad
$ \bigg \|\tilde{a}  \bigg \| + \bigg \| \tilde{b} \bigg \| $
\quad
$ \Bigg \|\tilde{a}  \Bigg \| + \Bigg \| \tilde{b} \Bigg \| $
\end{document}

enter image description here

Often, you will see the syntax employed of \bigl\| ... \bigr\| where the extra "l" and "r" indicate "left" and "right". While I originally was unsure if they actually affected the typesetting (or if they were purely a mnemonic to help the programmer keep track of matched delimiter sets), Gustavo and Mico (hat tip) assured me that their inclusion can affect the typesetting itself. Mico was kind enough to provide an example, which I recreate here. I commend his comment below to your attention:

\documentclass{article}
\begin{document} 
$ \big \|+\tilde{a}  \big \|  $
\quad versus \quad
$ \bigl \|+\tilde{a}  \bigr \| $
\quad
\end{document}

enter image description here

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