[texhax] Problem with eqnarray

[Modhurita Mitra]

Hi,
 	I am having trouble compiling my file which contains an eqnarray. 
At the third line in the following expression (the one beginning with 
- \cos, I get an error.

\begin{eqnarray}
  f(x,y,z) & = & P \times \\
  \exp \left \[ -\left( \frac{ \cos \theta \cos \phi (x - \mu_x) \\
                            + \sin \theta (y - \mu_y) \\
                   - \cos \theta \sin \phi (z - \mu_z)}{A_x} \right)^2 \\
            -\left(\frac{ \sin \theta \cos \phi (x - \mu_x) \\
                        + \cos \theta (y - \mu_y) \\
                  + \sin \theta \sin \phi (z - \mu_z)}{A_y} \right)^2 \\
  -\left( \frac{\sin \phi (x - \mu_x) + \cos \phi (z - \mu_z)}{A_z} 
\right)^2 \right \] \\
\end{eqnarray}

The error message says:
! Missing } inserted.
<inserted text>
                 }
l.270 ...- \cos \theta \sin \phi (z - \mu_z)}{A_x}
                                                    \right)^2 \\
?
! Extra }, or forgotten \endgroup.
<inserted text> }

l.270 ...- \cos \theta \sin \phi (z - \mu_z)}{A_x}
                                                    \right)^2 \\
?
! Missing } inserted.
<inserted text>
                 }
l.270 ...- \cos \theta \sin \phi (z - \mu_z)}{A_x}
                                                    \right)^2 \\
?

I cannot find any unbalanced }'s. And it get stuck at this point in an 
infinite loop, showing the same error again and again and doesn't compile 
any further. What could be the source of error?

Thank you,
Sincerely,
Modhurita Mitra