Why does the space have no effect in this line of my code?

Question

Here is my code:

\documentclass{article}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{geometry}
\geometry{a4paper}
\usepackage{amsmath}

\usepackage[frenchb]{babel}
\begin{document}

Number $2-a$:

\begin{align*}
Z &\longleftarrow \Phi(x,x) \\
Y &\longleftarrow Y +1
\end{align*}
Number $2-b$:
      \begin{align*}
IF x &\in A    GOTO E\\
Z &\longleftarrow \Phi(x,x) \\
Y &\longleftarrow Y +1
\end{align*}

\end{document}

And it looks like this (the problem is the red-circled line):

What should I do to make that line look like this where it looks more like handwriting where words are separated:

Answer 1

In math-mode spaces are ignored. (align as well as align*, equation etc. automatically swith to math-mode.) Just test $a b$: no space inside in the output. If you want to have spaces in math-mode, you could use explicit space (e.g. \␣ (slash space) or \hspace{1em}), but to get correct kerning and roman instead of italics format you should switch to text mode, i.e.

\text{IF }x&\in\text{A    GOTO E}

The \text command is supplied by the amsmath package which you already load anyway. Between A and GOTO there will be only one regular space, if more is needed the \hspace{1em} (in text mode!) could be used there.

Answer 2

use

\text{IF }x &\in\text{ A    GOTO E}\\

spaces in math mode have no effect.

Answer 3

In math mode, every element of text is assumed to be a variable, and typeset as such : in particular, for this matter, variables shouldn't form "words", that's why the texing engine won't display spaces. However, it is possible to print text "as if non in math mode", but you have to tell latex that it should regard that content as text.

Amongst the various commands you may use :

• \mathrm, \mathbf, etc (for mathematical text, such as function names : this won't give correct spacing as well!)
• \text from the amsmath package (for casual text, will use the font of the outer environment)
• \textrm, \textbf, etc. (in case you need specific font formatting -- the difference with the math equivalent is that you can use accented characters or inline maths inside these)

In your example, this works, for example :

\documentclass{article}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{geometry}
\geometry{a4paper}
\usepackage{amsmath}

\begin{document}

Number $2-a$:

\begin{align*}
Z &\longleftarrow \Phi(x,x) \\
Y &\longleftarrow Y +1
\end{align*}
Number $2-b$:
\begin{align*}
\mathbf{IF } x &\in A \mathbf{ GOTO } E\\
Z &\longleftarrow \Phi(x,x) \\
Y &\longleftarrow Y +1
\end{align*}

\end{document}

Note that as I said above, spaces are basically ignored in math display. So if you want your spaces to be taken into account, and your text to be separated from the rest of the sentence, you need to make sure the spaces are with the text, inside the braces.