CoCalc Public Filesnewcommand-in-jupyter-markdown-cell.ipynb
Author: Samuel Lelièvre
Views : 25
Description: To illustrate CoCalc issue #4569: "Jupyter markdown cells: newcommand and LaTeX formulas" -- https://github.com/sagemathinc/cocalc/issues/4569

# LaTeX, newcommand, Jupyter markdown cells, CoCalc

## LaTeX formulas with newcommand-defined bits in Jupyter markdown cells on CoCalc

This is to illustrate

## Experiment

Two markdown cells with the same bit of math, first not using \newcommand, then using it.

**Cell A**

We denote by $\operatorname{span}(u, v)$ the span of two vectors $u$ and $v$.

**Cell B**
$\newcommand{\span}{\operatorname{span}}$

We denote by $\span(u, v)$ the span of two vectors $u$ and $v$.


Cell A

We denote by $\operatorname{span}(u, v)$ the span of two vectors $u$ and $v$.

Cell B $\newcommand{\span}{\operatorname{span}}$

We denote by $\span(u, v)$ the span of two vectors $u$ and $v$.

## Observations

1. The formula is text in Cell A but an image in Cell B.
2. When viewing this Jupyter notebook in one's CoCalc project,
• in Cell A
• one can select text that includes the formula or part of it
• this selection can be done character by character
• the selected text gets highlighted in inverted colors (white on blue)
• the highlighting applies to the selected part of the formula as well
• in Cell B
• selecting some text, one can include the whole formula or none of it
• no way to select part of it, character by character
• highlighting in inverted colors does not apply to the formula if selected
• if "denote by span(u,v) the span" is selected, "span(u,v)" stays unhighlighted
3. If this Jupyter notebook is made public on the CoCalc share server
• in Cell A
• the formula "span(u,v)" gets rendered
• in Cell B
• the formula "span(u,v)" is missing

### Tentative explanation

Not really sure exactly what goes on but if I had to guess:

• KaTeX renders the formula in Cell A as text but the one in Cell B as an image.
• this explains the differences in highlighting
• this probably also explains the non-rendering on the CoCalc share server
• maybe the image lives in some hidden directory
• maybe it is not made public when the Jupyter notebook is