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I just got a short algorithm on my page, and it keeps getting aligned at the center of the page. But I want to have it aligned at the top, what do I have to do?

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Are you talking about an algorithm in a floating environment on a single page? However, it would be good if you show by a minimal example what you are doing. –  Thorsten Donig Sep 15 '11 at 15:44
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1 Answer

up vote 14 down vote accepted

To display a short algorithm (an object that LaTeX labels a "float") on a page by itself and to align it along the top of the page (instead of getting it to be centered vertically), try adding the following instructions to your document's preamble:

\makeatletter
\setlength{\@fptop}{0pt}
\setlength{\@fpbot}{0pt plus 1fil}
\makeatother

Happy TeXing! Note that by inserting these instructions in the preamble, their scope is global, i.e., they cover the placement of floats on all floats-only pages.


Addendum: I've been asked to explain what exactly this code snippet does. The LaTeX "kernel" (see latex.ltx, ca. line 7260) sets up several parameters to help position a float (or floats) on a floats-only page. Among these, the parameters \@fptop and @fpbot -- short for "floating page top" and "floating page bottom", I suppose -- govern how much space is inserted above the top float and below the bottom float on a floats-only page. The default value for both parameters is 0\p@ \@plus 1fil. (\p@ is defined earlier in latex.ltx to be equal to 0pt.) The component 1fil is "infinitely stretchable glue" (in TeX jargon), i.e., it will expand to take up all available space within its scope (here, the vertical page dimension not already occupied by other material -- such as the float itself!). Thus, the float(s) will be centered vertically by default on the floats-only page, and (happily) no unnecessary warnings about under-full pages will be issued by LaTeX.

To force the first float on a floats-only page to be top-aligned, then, it should suffice to issue the command

\setlength{\@fptop}{0pt}

The second instruction, \setlength{\@fpbot}{0pt plus 1fil}, is there mostly to "play it safe", just in case some package has been loaded that fiddles with the \@fptop and \@fpbot parameters in a way that would make LaTeX start issuing warnings about under-full pages on floats-only pages should you reset just the \@fptop parameter...

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That was exactly what I was looking for, thank you –  chris Sep 16 '11 at 18:47
    
@Mico Can I invoke this locally too, for example for 1 table? –  TomM Dec 28 '13 at 1:00
    
@Mico Sorry cannot edit my post anymore: I wanted to say for 1 table or for parts of the document, eg the appendix. –  TomM Dec 28 '13 at 1:18
    
@Mico I just tested it. Unfortunately it doesn't work in scrreprt :( –  TomM Dec 28 '13 at 12:16
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TomM: You're right! I will delete my previous, incorrect comment. (By the way, simple "localizing" the redefinitions of \@fptop and \@fpbot fails not only with scrreprt but also with the "standard" LaTeX document classes article, report, and book.) May I suggest you create a new posting in which you'd ask for a solution to the objective of localizing the scope of these parameters? –  Mico Dec 30 '13 at 14:10
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