% $Date: 2004/10/04 17:25:12 $ $Author: nthiery $ $Revision: 1.1.1.3 $

\begin{Mhelppage}{SfAVars}{V. Prosper}

  \begin{MInfo}
    \eng{specifies valid variables in alphabets}
  \end{MInfo}

  \begin{MCalls}
    \Mcall{vset}
  \end{MCalls}

  \begin{MParameters}
    \param{vset}
    \eng{a set of variables} 
  \end{MParameters}

  \begin{MIntro}
    \eng{The {\Mthis} function specifies which variables are
      considered for the \Mex{SfAExpand} function.
 
      \Mex{vset} gives the set of valid variables for \Mex{SFA}, for
      instance:
      \begin{itemize}
      \item
        {\Mex{\{ x1, x2, x3 \}}}
      \item
        {\Mex{\{ \{x\}, \{y\} \}},    all the \Mex{x}i's and \Mex{y}i's,}
      \item
        {\Mex{\{ \{x\}, \{y\}, t \}} all the \Mex{x}i's and \Mex{y}i's, and the 
          variable \Mex{t}.}
      \end{itemize}
      
      With no argument, {\Mthis} returns the current set of valid
      variables.
      
      Note that each call to {\Mthis} destroy the remember table of
      \Mex{SfAExpand}, if \Mex{vset} is specified.  }
  \end{MIntro}

\begin{MExample}{ex1}
\begin{Mexin}
muEC::SFA::SfAVars( {{x}, u, v} );
\end{Mexin}
\begin{Mexout}
                          {{x}, u, v}
\end{Mexout}
\begin{Mexin}
tt := muEC::SFA::SfAExpand( m[3,2](x1+u+v) - q*s[2,2](x1+u+v) );
\end{Mexin}
\begin{Mexout}
 3  2    3   2    2  3      2  2      2         2   3
u  v  + u  x1  + u  v  - q u  v  - q u  v x1 + u  x1  -

      2   2        2              2    3   2    2   3
   q u  x1  - q u v  x1 - q u v x1  + v  x1  + v  x1  -

      2   2
   q v  x1
\end{Mexout}
% \begin{Mexout}[hide]
% q*u*v*x1^2*(-1) + q*u*v^2*x1*(-1) + q*u^2*v*x1*(-1) + u^2*v^3 +
% u^3*v^2 + u^2*x1^3 + u^3*x1^2 + v^2*x1^3 + v^3*x1^2 + q*u^2*v^2*(-1) +
% q*u^2*x1^2*(-1) + q*v^2*x1^2*(-1)
% \end{Mexout}
\end{MExample}

\MRelatedFunctions{SfAExpand}
\end{Mhelppage}
