function result = plot_function( f_name )
% f_name is the name of a built-in or user-defined function
[f,msg] = fcnchk( f_name ); %, 'vectorized' );
if length(msg)>0
    error(msg)
end
x = -10 : 0.1 : 10 ;
y = f( x ) ;
plot( x , y )