LaTeX forum ⇒ Math & Science ⇒ Why is command \textendash invalid in math mode?

[yaozhao]

Code: [Select all] [Expand/Collapse] [Download] ({untitled.tex})

\[Q_O^D = 75 – 5 P_O + P_C + 2I\]

Overleaf gives command \textendash invalid in math mode on input line 34.
(34 is the line of this code in my file)

But it can still give my pdf. Why is this warning? What's the meaning? Should I just ignore it?

[Ijon Tichy]

The warning message is, because you've used an endash: –, instead of a minus: -, in your equation. You should not ignore the message, but change your equation like here:

Code: [Select all] [Expand/Collapse] [Download] ({untitled.tex})

\documentclass{article}
\begin{document}
    \[Q_O^D = 75 - 5 P_O + P_C + 2I\]
\end{document}

BTW: Please always post a minimal working example instead of a code snippet. (Note: Because of the one line code snippet, I've made my own MWE for my first studies and just input the one line instead of copying it with the result, that I had no error or warning. With a real MWE I've never hit on the idea to not copy your code. So one more reason for real MWEs.)

[yaozhao]

I see. Yes, after using your code, the warning message disappeared. But how to type minus in my Mac?

[yaozhao]

Code: [Select all] [Expand/Collapse] [Download] ({untitled.tex})

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align*}
 Q_O^D &= 75 – 5 P_O + P_C + 2I \\
 Q_O^D &= 75 – 5 P_O + 5 + (2\times 10) 
\end{align*}
\end{document}

Overleaf gives command \textendash invalid in math mode on input line 34.
(34 is the line of \end{align*})

But it can still give my pdf. Why is this warning? What's the meaning? Should I just ignore it?

[Ijon Tichy]

Depends on the keyboard layout/locale. AFAIK on a German or US keyboard type the - one time without AltGr or similar modifier key.

[Ijon Tichy]

Please don't open a new thread for the same question. If you have additional information (like a minimal working example) add them to the already existing question (or a new posting at the thread of that question).

[yaozhao]

Not the same question. The problems are different.

[Ijon Tichy]

No, it's exactly the same. Again, you've used – instead of -. With - it works:

Code: [Select all] [Expand/Collapse] [Download] ({untitled.tex})

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align*}
 Q_O^D &= 75 - 5 P_O + P_C + 2I \\
 Q_O^D &= 75 - 5 P_O + 5 + (2\times 10) 
\end{align*}
\end{document}

[cgnieder]

I have merged both topics as they are essentially the same post.