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Title says it all. What's more common? Is there one to prefere (maybe due to some norm)?

This:

$\operatorname{\mathfrak{R}} z, \operatorname{\mathfrak{I}} z$

or that:

$\operatorname{Re}z, \operatorname{Im}z$ ?

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  • 4
    $\begingroup$ It's not "fractal". It's "fraktur". Wikipedia. $\endgroup$ – kahen Nov 10 '12 at 15:55
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    $\begingroup$ This is an opinion question which is hard to answer. My own sense is that the fraktur notation is a bit older and less common nowadays. $\endgroup$ – Cheerful Parsnip Nov 10 '12 at 15:58
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    $\begingroup$ Because of Latex I'm actually here. I was wondering if there's a special reason why Latex defaults \Re and \Im to the Fraktur versions. $\endgroup$ – Foo Bar Nov 10 '12 at 16:05
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    $\begingroup$ I see $\operatorname{Re}z, \operatorname{Im}z$ more often. $\endgroup$ – Martin Thoma Oct 29 '13 at 13:43
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    $\begingroup$ @GrumpyParsnip It's not an opinion question. Perhaps it's poorly defined what population to consider and how to measure, but after that's it's "just" a matter of measuring the the frequency and tell which is more common. $\endgroup$ – skyking Sep 25 '15 at 6:46
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I lean towards readability and I find $\operatorname{Re}z$ and $\operatorname{Im}z$ unambiguously clear.

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    $\begingroup$ Tastes vary, of course, but not being able to write or even recognize fraktur tends to favor readability. The fact that $\mathfrak{A}$ looks like an $U$, not an $A$, and $\mathfrak{P}$ looks like a $B$, not a $P$, has always slightly annoyed me. $\endgroup$ – lhf Aug 24 '15 at 11:10
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    $\begingroup$ Just becaue you lean one way or another doesn't make it more or less common. $\endgroup$ – skyking Sep 25 '15 at 6:51
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    $\begingroup$ @lhf I cannot believe your $\mathfrak{A}$ was actually an $A$ because it looks like a $U$, $\mathfrak{U}$ is $U$! $\endgroup$ – Alec Teal Dec 20 '15 at 19:27
  • $\begingroup$ Oh I see it now. $\endgroup$ – Alec Teal Dec 20 '15 at 19:28
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I prefer the fraktur notation. Firstly, it looks much more elegant. Secondly, it is unambiguous (for instance, Re is often used for Reynolds number).

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    $\begingroup$ And "Im" (or "im") is often seen as the image of a linear transformation. +1 $\endgroup$ – manooooh May 14 at 0:07

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