# How to tell Mathematica not to simplify an expression

While there is this question with a very similar title, it does not answer my question, which is:

I have part of an input, in my case

Re[Exp[I*x]]


which Mathematica "simplifies" to

Cos[Re[x]]/E^Im[x]


So I am wondering how to tell Mathematica to leave this expression, whether it's alone or part of a longer formula, in its previous form rather than to change it as shown here.

### Update

I should probably add I am still running version 6, hoping this is not causing the issue.

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I can not reproduce your problem. Re[Exp[I*x]] does not automatically simplify to anything. Evaluating it leaves it unchanged. Evaluating Re[Exp[I*x]] // Simplify doesn't change it either. –  m_goldberg Jul 15 '13 at 12:47
Maybe this is because I am still running Mathematica v6? But should it behave differently in such a way? If I evaluate Re[Exp[I*x]] in a new notebook, I get the above expression. –  Bernd Jul 15 '13 at 12:51
i agree with @m_goldberg, but if you want to suppress on the fly simplification from Mathematica enclose it in a HoldForm expression. Is that what you're asking for? –  Stefan Jul 15 '13 at 12:51
@Stefan, HoldForm might work but it seems be a little tricky to use in this case if I want to use the expression in a longer formula e.g. involving slots (#) where the evaluation must not be stopped. I was hoping there would be some solution of the form expression //SomeForm? –  Bernd Jul 15 '13 at 12:58
@Bernd what about Defer@Integrate[x^# Exp[-x], {x, 0, 1}]&/@Range[2] ? –  Stefan Jul 15 '13 at 13:07

In case you want Mathematica to suppress on the fly simplification and having slots (#) involved, you might consider using Defer:
Defer@Integrate[x^# Exp[-x], {x, 0, 1}]&/@Range[2]