I use the following codes

\usepackage[latin1]{inputenc} %écrire directement les accents 
  % ------------------------------------------------------------
   % ------------------------------------------------------------
 $\displaystyle\lim_{n\longrightarrow\infty}\langle {\bf T} x_n\; 

When I compilate I get

enter image description here

I want to decrease the size of the number (1+i)/2.

Thank you!


You can use \tfrac, though an inline fraction may be better:

Sample output




   \lim_{n\to\infty}\langle \mathbf{T} x_n\mid
   x_n\rangle_A=(\tfrac{1+i}{2},0,0) = ((1+i)/2,0,0)


I have remove irrelevant packages and improved the coding. Note in particular,

  • \to instead of \longrightarrow
  • \mathbf{T} instead of {\bf T}
  • \mid instead of \;|\;
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  • tank you very much for your help. What are the necessary packages for mathematical papers? I use the following: \usepackage{amssymb,amsmath,amsthm,latexsym,mathrsfs,amsfonts,dsfont} – Student Dec 23 '17 at 10:14
  • @Student That is a reasonable selection of packages, but it depends exactly what type of mathematics constructs you need - look up their documentation either on ctan.org or via texdoc ... to see what they do. Also remember the mathtools package that extends amsmath. – Andrew Swann Dec 23 '17 at 11:01
  • ... which can be loaded in the place of amsmath, since it loads it. – Bernard Dec 23 '17 at 11:18
  • @AndrewSwann Thanks you. I mean what are the necessary mathematical packages for a standard mathematical papers? – Student Dec 23 '17 at 11:30
  • 2
    @Student There is no fixed standard list of such packages - mathematicians keep inventing new notation... – Andrew Swann Dec 23 '17 at 12:23

Some improvements and suggestions: loading mathtools and xparse, one can define an \innerp command, which displays an inner product typeset in a ‘natural’ way: both arguments are grouped and separated by a comma. The delimiters can be adjusted automatically to the contents with the \innerp* command, or manually with an optional argument: \big,\Big,\bigg or \Bigg.

In addition, I loaded the nccmath package, which defines medium-sized commands (~ 80% of \displaystyle), among which \mfrac, often looking better than \tfrac:

\usepackage{mathtools, nccmath}

\NewDocumentCommand{\innpargs}{ >{\SplitArgument{1}{,}}m }
\NewDocumentCommand{\innpargsaux}{ m m }


   \lim_{n\to\infty} \innerp[\big]{\mathbf{T}x_n, x_n}=\Bigl(\mfrac{1 + i}{2},0,0\Bigr)=\Bigl(\mfrac{1}{2}(1 + i),0,0\Bigr)


enter image description here

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  • Thank you for your answer, according to your answer, mathtools can replace amsmath? – Student Dec 24 '17 at 8:57
  • It doesn't exactly replace amsmath, it's an extension, and loads it, so needless to load it twice. – Bernard Dec 24 '17 at 10:57

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