raining.

<p>The fields in <CODE>mixparams</CODE> are
<PRE>

  type = 'mdnmixes'
  ncentres = number of mixture components
  dimtarget = dimension of target space
  mixcoeffs = mixing coefficients
  centres = means of Gaussians: stored as one row per pattern
  covars = covariances of Gaussians
  nparams = number of parameters
</PRE>


<p><CODE>[mixparams, y, z] = mdnfwd(net, x)</CODE> also generates a matrix <CODE>y</CODE> of
the outputs of the MLP and a matrix <CODE>z</CODE> of the hidden
