# How can I control the size of a multi-line equation?

1. Jun 4, 2009

### S_David

Hello,

I have two questions:

1- How can I control the size of a multi-line equation?
2- In a multi-line equation, I always need to open a brace in one line and end it at another line. But the problem is by using the following code:
Code (Text):

\begin{split}
X=&\left\{.....\right.\\
& \left. .... \right\}
\end{split}
the two braces are not always of the same vertical length. How to solve this problem?

Last edited by a moderator: Oct 18, 2011
2. Jun 5, 2009

### CompuChip

Re: Latex Help

In the first question, what do you mean by the 'size'?

For the second one: I haven't tested this, but you might try something like
Code (Text):
\newcommand\twolines{3}{\ensuremath%
\begin{split}%
#1 = &\left\{\vphantom{#2}#1\right.\\%
& \left. \vphantom{#1}#2 \right\}%
\end{split}%
}
and then use it like
Code (Text):
$\twolines{X}{stuff on the first line}{stuff on the second line}$
The trick lies of course in the use of \vphantom.

The quick-and-dirty way is to just make the brackets "by hand", so instead of \left and \right use \big, \bigg, \Big, etc.

3. Jun 5, 2009

### minger

Re: Latex Help

I've personally never ran into this problem, but if I did, that would be the approach I would take.

I will have to take a look at that phantom command though...

4. Jun 5, 2009

### S_David

Re: Latex Help

I mean the font size, because I have very long equations which takes much space in each page.

5. Jun 5, 2009

### fatra2

Re: Latex Help

Why don't you make a line-break at some point so that the equation continues on the next line. This would preserve any unpleasant topography for the reader, and would assure that the equation doesn't overflow the page.

You can do this line break with a simple \\ wherever you want. Doing so, every part of your equation will be center aline. If you want to aline the equation specially, you can use && on each line.

Cheers

6. Jun 5, 2009

### S_David

Re: Latex Help

My equations are not single line, but multi-line equations, so I already did the line-break. But my request is: how to make these equations small enough to span a reasonable space on the page?

7. Jun 5, 2009

### fatra2

Re: Latex Help

My remark is simple. If you have very long equations, and you change the font size, the reader might lose reading comfort, due to their overfullness.

I firmly believe that you should leave the font the way they are, and just make line-break to make them comprehensible. You will gain in reading comfort, which is probably why you use LaTeX.

Cheers

8. Jun 6, 2009

### S_David

Re: Latex Help

How do we know, if we don't try? Let us try it, and then we decide.

9. Jun 8, 2009

### fatra2

Re: Latex Help

Ok,

Here it goes. The font size in math mode are predefined in LaTeX. Therefore, a simple \fontsize or \Large only gives you a warning. This is due to a misunderstanding between the command given and the actions to be taken by the compiler.

Once in math mode, you can change the font size with the
Code (Text):
{\...style}
command. For example,
Code (Text):
{\displaystyle }
will appear full size. There are similar commands \textstyle, \scriptstyle, and \scriptscriptstyle.

Cheers

10. Jun 8, 2009

### S_David

Re: Latex Help

I want to make them of font size 10 pt, for example, how can I do that using the commands you presented?

11. Jun 8, 2009

### fatra2

Re: Latex Help

Hi there,

The easiest way to do so, is to put the whole document to 10pt. You can do so within the doucmet class declaration : \documentclass{10pt}{report/book/article/letter}, and there you go, your math mode will also be at 10pt.

Otherwise, you will have to look at the size that suits from the different styles mentioned before.

I am sorry that I cannot be anymore help. It's just that you are writing in LaTeX, meaning that you might have a different point of view than the compiler for the layout. I stick with my suggestion from before, that the compiler might not be so bad.

Cheers

12. Jan 16, 2010

### Artemida

Re: Latex Help

Dear David
Did you found any simple command in LaTex for your 2nd question regarding splitting of the long equation in the brackets? I have the same problem now. Beforehand thank you.

13. Jan 17, 2010

### S_David

Re: Latex Help

Just use the commands \Bigg(Your Equation ....................................................................................................................................\Bigg). This is the simplest way to solve this issue.

Regards

14. Jan 17, 2010

### Artemida

Re: Latex Help

thank you