When writing an equation in the "math labell" environment, if the equation is too long, how do I break it to several lines? The LaTeX solution of using \\ doesn't seem to work.

I think there is a major problem… When you use [[math]] tag, the underlaying LaTeX processor assumes that your equation is within the

```
\begin{equation}
...
\end{equation}
```

But when you want to break the long equation you usually use a construct like this:

\begin{eqnarray}

10xy^2+15x^2y-5xy & = & 5\left(2xy^2+3x^2y-xy\right) \\

& = & 5x\left(2y^2+3xy-y\right) \\

& = & 5xy\left(2y+3x-1\right)

\end{eqnarray}

which does not use the `equation` environment… I do not know (yet) how to solve this problem. Can you force line breaks within the `equation` environment?

michal

Michał Frąckowiak @ Wikidot Inc.

Visit my blog at michalf.me

I have no idea if there's a way to force line breaks in equation environment.

Is it possible to have the [[math]] tag assume that you always want an eqnarray environment? (I can't see any downside to always using eqnarray)

In any case, thanks for replying quickly, and congratulations for designing and maintaining such a wonderfull wiki farm.

I think the way to go would be to implement the structure:

```
[[math type="eqnarray"]]
... loooong equation ...
[[/math]]
```

Very few people would use it indeed but it would be possible to break equations nicely. Does it sound reasonable?

Michał Frąckowiak @ Wikidot Inc.

Visit my blog at michalf.me

Sure… I have no idea how to implement it, and agree that it's a low priority task as few people will need it.

Is it hard to do?

Hi, and happy new year.

I found this example for a line break in the equation environement:

\begin{array}{rcl}

\sin x & = & x -\frac{x^{3}}{3!} +\frac{x^{5}}{5!} - {} \\ & & {} -\frac{x^{7}}{7!} + \cdots

\end{array}

I'm not sure but wouldn't a structure [[math type="eqnarray"]] cause a equation numbering problem?

No problem at all, look below:

(1)Referencing should also work: Eq.(1) — but you will not get a label hint when using the button from the editor (ups). This is to be fixed some time ;-)

```
[[math label1 type="eqnarray"]]
\lefteqn{ \cos x = 1
-\frac{x^{2}}{2!} +{} }
\nonumber\\
& & {}+\frac{x^{4}}{4!}
-\frac{x^{6}}{6!}+{}\cdots
[[/math]]
[[math type="eqnarray"]]
x & = & \frac{1}{2}at_1^2 + v_0t_1 + x_0\\
& = & \frac{1}{2}gt_1^2\\
t_1^2 & = & \frac{2x}{g}\\
t_1 & = & \sqrt{\frac{2x}{g}}\\
& = & \sqrt{\frac{2(1 m)}{9.8 m/s^2}}\\
& = & {\bf 0.45 \; seconds}
[[/math]]
```

Please check if it works in your cases and I will add the `type="eqnarray"` to the documentation if there are no problems with this.

I hope Wikidot could be adopted and recognized in science-related communities some time… ;-)

**And a HAPPY NEW YEAR too!** — I am just writing a New Year Newsletter to all the users, full of New Year's resolutions related to Wikidot ;-)

Michał Frąckowiak @ Wikidot Inc.

Visit my blog at michalf.me

Impressive! ;)

I just wondered because of the difference between **\nonumber\\** and the simple **\\** line break in eqnarray.

Another not that important numbering thing: if one embeds pages with [[include]] then the equations have different numbers than on the original page. That's ok, most of the time a consecutive numbering is what you want. But it seems that all inline math is counted too. Here is an example. The first equation gets number 5 and there are precisely five inline math symbols above.

Maybe it would be more consistent if the numbering was bound to the first header level so that equation 3 of chapter 2 gets number (2.3). Just a thought…

forget about ** \nonumber\\** — I have just copied&pasted it from another example I have been testing. LaTeX internal numbering is disabled anyway so

`\nonumber`has no effect.

And thanks for pointing me to your numbering example. So here it goes:

- When you include a page what is really done is that before wiki compilation the source of the included page is simply inserted. So the equation numbering will be from 1 to
*n*and does not have to reflect the numbering in the original page - There was a bug (now fixed hopefully) with numbering/including combination. Now it should work better. You can recompile the page and the misnumbering should never appear again. Thanks for this one!!!

Alternative equations numbering… It would be a bit more complicated because both the wiki engine and the "why" problem… Anyway — I think it is much easier in general to have equations numbered from 1 to *n* without (sub)sections.

Goon: I can see you are using Wikidot for quite interesting things ;-) I am glad you find it useful!!!

michal

Michał Frąckowiak @ Wikidot Inc.

Visit my blog at michalf.me

Hey, thanks! It's fixed now.

Regarding the alternative equations numbering: Actually it is the first time that i have to bother with such subtleties like numbering equations, chapters or bibliographies. I'm glad that wikidot automates most of it. Nevertheless, i've noticed that in scientific literature, (sub)sections are labeled in the form 2.3.1 whereas equations and image captions are consecutively counted per main chapter (e.g 2.10.b). I can't tell why. Another "why": html lists don't support this scheme.

Well, what was the original question of this thread …, to make a break?

Thanks for the new module type. There's nothing like neatly aligned equals signs to get *"adopted and recognized in science-related communities"* ;)

.equation-number{

float: right;

font-size: 110%;

}

Just change that in your theme, put either a font-size of 0 or a invisible font color.

Using an "invisible" font colour or setting the font size to zero is not usually CSS best practice, better to use something like:

```
.math-equation {
display:none;
}
```

although of course this will affect all equations in your wiki.

Rob

**Rob Elliott** - **Strathpeffer, Scotland** - Wikidot first line support & community admin team.

Hey, I would use this simple syntax:

\begin{equation}

\begin{split}

equation 1 \eqution 2\…

\end {split}

\end{equation}

it allows you to split long equations in different lines, no problem with the numeration.

Hope it's useful!