Negation of convergence symbol?

Question

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How to look up a math symbol?

How do I express the opposite of convergence?

I would type $x\rightarrow 0$ to say that x converges to 0, but how can I make the crossed out \rightarrow appear

Answer 1

The amssymb package offers \nrightarrow:

\documentclass{article}
\usepackage{amssymb}

\begin{document}
\[
  a_n \nrightarrow 0.
\]
\end{document}

A similar symbol is also available using the same command with the MnSymbol and mathabx packages (mathabx changes the shape of many other symbols).

Whenever you need a symbol, you have two initial resources:

1. You can look things up in the Comprehensive LaTeX symbols list.

2. You can try Detexify, which allows you to draw the symbol and tries to recognize your drawing.

Answer 2

You could prefix \not to whatever symbol (e.g., \to) you select for "convergence", as in $x\not\to 0$. (\to is a synonym for \rightarrow...)