outputing tex into a file given by a variable



Hi 

I am trying to output some tex into a file whose
name is a variable.

I have tried 

tex(<maxima_expression>,file_name)

which, instead, outputs into a file whose name
is name of the variable file_name
and not the name given by the string contained in file_name.

Is there a workaround for this problem?

  Fabrizio