Use new fonts in MiKTeX

I'm using MiKTeX and TeXnicCenter and I'm trying to change the font for some parameters in mathematical formulas. Specifically, I would like to use capital letters of font "Libris". Is this possible? This font is listed in the LaTeX Font Catalogue and, according to the MiKTeX Package Manager, the package libris is installed. I don't know if this information is useful, but I haven't used LaTeX for much time until now.

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Let's see if I understood your question correctly: You want all capital letters in mathematical formulas to be in Libris, and everything else to remain in the standard font? –  doncherry Sep 1 '11 at 18:26

\usepackage{libris} should allow you to use this font.

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Yes, "should" is the right word :) I've already tried in that way and even with the help of mirror.switch.ch/ftp/mirror/tex/fonts/libris/doc/fonts/libris/… but with no success. When I try to write \textsf{...}, i get an error message: [DocOpen("%bm.pdf")][FileOpen("%bm.pdf")] Cannot execute the command. Even $\mathsf{...}$ doesn't work, as I get the usual sans serif font. –  Criscpas Aug 2 '11 at 23:52
Can you provide a minimal working example so we can try and reproduce it? –  ℝaphink Sep 1 '11 at 16:20

In case you don't mind using XeLaTeX or LuaLaTeX you can use any font that is installed in your system by means of package fontspec. Something on the following lines should do it

\usepackage{fontspec}
\setmainfont{fontname}

As an additional benefit you gain the advantage of using OpenType font features.

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Have you tried something like \renewcommand\sfdefault{yly} ?

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Thank you all, I managed to do what I was trying to do by defining the command \newcommand\mt[1]{\fontfamily{yly}\selectfont\textit{\emph{#1}}}. I didn't want to have a new default sans serif font: just to make the capital letters of libris available for some mathematical objects. The problem was just TeXniccenter: as I was advised to install TeXstudio instead, it solved by itself. Thank you once more. –  Criscpas Nov 16 '11 at 22:44