# Controlling space between two words in the body of text

In my thesis I'll have equations that are labelled (1) through to (20).

In the body of the text I'll refer to them as Eq. (1),..., Eq. (20), for example. The problem is that LaTeX will change the spacing between Eq. and (1), as it does with the spacing between any two separate words, in order to fill the margins. This looks ugly.

How do I fix this?

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Eq.~\ref{equationNUMBER} might help –  PattaFeuFeu Nov 4 '12 at 13:48
@PattaFeuFeu Not only it might help, it is the correct way to write. Please, supply an answer. –  egreg Nov 4 '12 at 13:54
@egreg -- but a ~ (tie) won't keep the space uniform; it will only ensure that "Eq." is not separated from the number. of course, that's the right thing to do, but not what is asked. for that, a fixed space, either \, or \; would be better. \; is defined only for math use, which is a nuisance, so maybe an explicit \nobreak\kern.3em would be preferable. –  barbara beeton Nov 4 '12 at 14:03
@barbarabeeton ~ is equivalent to \nobreak\  which of course inserts a normal space (not affected by the space factor). IMO it's better that all spaces on a line have the same width. Probably Jase's problem is just due to the extended space after periods. –  egreg Nov 4 '12 at 14:09
@egreg -- good point. i concede. (it's still morning here.) –  barbara beeton Nov 4 '12 at 14:23

Using Eq.~\ref{equationNUMBER}, where equationNUMBER is the value you set for the equation’s label, does what you want. The tilde is a non-breaking space to ensure that the connected parts (Eq. and your reference) stay connected.
The answer should say that a space after a period is "usually" anlarged (indicating a sentence ending). Both ~ as well as \  will produce a normal interword space (the former also preventing a line break). –  Frank Mittelbach Nov 4 '12 at 14:15