How to write a diagup line over a mathematical formula in LaTex

I thought this problem about two days! I used the google engine to search some solution to this problem, I have not got the answer, I read the Latex companion carefully about 300 pages, also not get the answer. At the naight of the second day, I thought out a solution for this problem just a moment.

Where that problem come from? A paper I read has that simbol like this , I can’t use latex to typeset that for a presentation.

Now the problem is solved perfectly by me. The source code for Latex is like this:

\usepackage{tikz}
...
$\langle x, x \rangle \!\!\!\!\!\!\!\!\!\!\!\!\!\!\tikz{\draw(0pt,0pt) -- (23pt,6pt);}$
...

Note that the compiling order is LaTex –> dvi2ps –> ps2pdf. 采用上面的方法虽然产生了正确的结果，但是文档中插入的eps图片都消失了。

如果想采用编译顺序LaTex –> dvi2pdf的话，需在\usepackage{tikz}的前面加上\def\pgfsysdriver{pgfsys-dvipdfm.def}这样，图片也保留了，也产生了正确的结果。