please help me to find out the inverse this function,  

 $$f(x)=\frac{e^x+e^{-x}}{e^x-e^{-x}}$$
I know that, let  

 $$y=\frac{e^{x}+e^{-x}}{e^{x}-e^{-x}}$$
and if I find $x=\cdots$ then that is the inverse. But I can't calculate this. Is this the only way. is there any other way to figure it out?