>
> Maybe http://www.emacswiki.org/emacs/ScimBridge will help? It appears
> to let Emacs control scim by talking to scim-bridge over a socket.
> Perhaps you could adapt parts of it to switch input languages
> programmatically.


no , it is between buffers.
I want to revise cdlatex using function "texmathp" .
Now I am studying elisp.
Thanks