# Re: formula numbering

```On 2013-08-08, bieniasz wrote:
> Richard Heck <rgheck <at> lyx.org> writes:```
```
>> What happens, then, when you add a new equation somewhere in
>> the middle of the document?

> This is what LyX already does - it updates automatically the equation
> numbers. My point is why one cannot use these numbers for referencing
> the equations in the text, since they are already there, up-to-date.

But how do you find out the up-to-date number of the equation in chapter
3 you want to reference in chapter 14?

...

> LaTeX users are primarily
> scientists who write scientific texts. In such text one ALWAYS
> refers to equations by numbers, and not by any peculiar labels.

Reference by numbers is used in the printout, but reference by label is used
in all LaTeX source documents.

In the printed text, I usually use a description of the formula + the
reference number so that the reader can look it up if required but generally
does not need to:

The incident radiation is absorbed and distributes in the sensor layer
by means of heat conduction (Equations [15] and [16]) resulting in a
time-dependent temperature field T(\xyz,t).

>> Still, making up a label isn't that hard, and it can make it easier
>> to remeber which equation you want to reference later. You can
>> of course just use numbers if you wish.

> Well, yes and no. If I use my own labels, like
> E1, E2, E3 etc., then I am in trouble when I need to add something
> between E1 and E2, let's say. The problem is that user-defined labels
> are not automatically updated, whereas the real equation numbers are.
> Hence, I have a mess in which labels are in no clear relation to
> the numbers.

But IMO, the even bigger problem is, if you insert a new formula between
E1 and E2 but continue to use E15 for new references to the "heat
equation" (or whatever) which is now E16!!!

> So, in conclusion, I daresay the LaTeX/LyX system for equation numbering
> needs a reasonable revision. If there are any LyX programmers out there,