Take the 2-minute tour ×
TeX - LaTeX Stack Exchange is a question and answer site for users of TeX, LaTeX, ConTeXt, and related typesetting systems. It's 100% free, no registration required.

Using beamer. Let's say I want to write A+B but with the plus invisible in one slide and visible in the next one. I think I read somewhere that more space is left normally around the + for being a binary operator. It seems to be that A\phantom{+}B leaves only the space of the sign +. How can I get all the space I need.

share|improve this question
    
I don't think the beamer tag is relevant here. –  Quinn Culver Sep 23 '11 at 18:17

2 Answers 2

up vote 10 down vote accepted

Need to add additional {} which emulate a binary operator as TeX thinks there is something on either side of the +:

$A\phantom{{}+{}}B$
share|improve this answer
    
What is the difference between your answer and Stefan's? Is one better? –  Quinn Culver Sep 23 '11 at 15:34
    
@Quinn: AFAIK both add identical spacing around the symbol for a binary operator, but the \mathbin better captures the intent of what you are doing. –  Peter Grill Sep 23 '11 at 15:47
    
When I use &\phanom{=}H... on one line of an align environment and then &=H... on the next, they are misaligned, and using (either of) your trick(s) works. According to your (and Stefan's) explanation, this is because the first = one is not a binary operator whereas the second = is. Am I correct in deducing that the reason the second = is considered a binary operator is because TeX considers the text at the end of the previous line to be to the left of =? –  Quinn Culver Sep 23 '11 at 18:16
    
Not exactly sure I fully understand, perhaps it is best to post an additional question with a full MWE, but using F&\phantom{{}={}}H should produce the proper spacing. –  Peter Grill Sep 23 '11 at 18:26

Use \mathbin for making the invisible symbol a binary operator:

$A\mathbin{\phantom{+}}B$
share|improve this answer
    
What is the difference between your answer and Peter's? Is one better? –  Quinn Culver Sep 23 '11 at 15:34
    
I would think @Stefan's answer is more clear, since you literally define \phantom{+} to act like a binary math operator (via \mathbin. In my opinion, one would only obtain @Peter's solution through experience with this problem, or perhaps a couple of compiles to see whether the spacing is correct. –  Werner Sep 25 '11 at 14:33
1  
@Werner: The spacing will be identical. The {} on either side of the + lets TeX know that there is an item of zero width on either side of the +. But, I do agree that in this case, that \mathbin more clearly captures the intent. –  Peter Grill Sep 25 '11 at 22:00
2  
they may work the same in \phantom, but they dont at the beginning of a line. if i start a line with a logical and, it will attach to the next variable like a unary operator, \mathbin doesnt fix this, {} does. –  peter Nov 23 '12 at 10:44

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.