fix eqnarray

cpp/kspace.cpp

@@ -433,6 +433,10 @@ int kspace<be, dt>::filter(
  *  a Gaussian filter and a sharp real space spherical filter.
  *
  *  Filter expressions in real space are as follows:
+ *  \rst
+ *  .. math::
+ *      :nowrap:
+ *
  *      \begin{eqnarray*}
  *          \phi^b_\ell(r) &=&
  *              \frac{1}{\ell^3}\frac{6}{\pi} H(\ell/2 - r) \\
@@ -443,7 +447,14 @@ int kspace<be, dt>::filter(
  *              \frac{1}{2 \pi^2 r^3}
  *              \left(\sin k_\ell r - k_\ell r \cos k_\ell r\right)
  *      \end{eqnarray*}
+ *
+ *  \endrst
+ *
  *  and the corresponding expressions in Fourier space are:
+ *  \rst
+ *  .. math::
+ *      :nowrap:
+ *
  *      \begin{eqnarray*}
  *          \hat{\phi^b_\ell}(k) &=&
  *          \frac{3}{2(k\ell/2)^3}
@@ -453,6 +464,8 @@ int kspace<be, dt>::filter(
  *          \hat{\phi^s_\ell}(k) &=& H(k_\ell - k)
  *      \end{eqnarray*}
  *
+ *  \endrst
+ *
  *  \f$\sigma_\ell\f$ and \f$k_\ell\f$ are calibrated such that the energy of
  *  the large scales is approximately the same (within the inertial range)
  *  independently of the shape of the filter.