# Noparse

#### topsquark

##### Well-known member
MHB Math Helper
I have a question about how to use "noparse." I stole the code from one of MarkFL's recent posts. Here's what I am trying to do, but it's not supposed to carry out the line commands. I don't know why it isn't working.

$$f(x)=\begin{cases}1 & x\in\mathbb{Q}\\ 0 & x\notin\mathbb{Q} \\ \end{cases}$$

-Dan

#### MarkFL

Staff member
Re: noparse

I actually tried to use the noparse tags in that post, but ran into the same problem, so being pressed for time, I simply went with the code tags.

#### Jameson

Staff member
Re: noparse

I have a question about how to use "noparse." I stole the code from one of MarkFL's recent posts. Here's what I am trying to do, but it's not supposed to carry out the line commands. I don't know why it isn't working.

$$f(x)=\begin{cases}1 & x\in\mathbb{Q}\\ 0 & x\notin\mathbb{Q} \\ \end{cases}$$

-Dan
This is strange. The noparse tag actually works as you can see here:
$$x^2$$

For some reason though this code on its own with no dollar signs renders Latex. I have no idea why.
Code:
\begin{cases}1 & x\in\mathbb{Q}\\ 0 & x\notin\mathbb{Q} \\ \end{cases}

#### Klaas van Aarsen

##### MHB Seeker
Staff member
Re: noparse

vBulletin always executes the begin{cases} latex environment directive, regardless what's around it.
You don't even need [tex] markers to make it work.

MHB Math Helper
Thanks all.

-Dan