vlt.math.mod_ellipse_on_mvnpdf_x0

  ELLIPSE_ON_MVNPDF_X0 - Calcluate 'response' of an ellipse on multivariate normal

   Y=vlt.math.ellipse_on_mvnpdf_x0(X,ELLIPSE_PARAMS,XMESH,YMESH)

   Computes the overlap of an ellipse on a multivariate normal distribution.

   This form facilitates passing to LSQCURVEFIT because the parameters MU and
   SIGMA are all passed in a vector, X0

   Inputs:
     X0 - A vector with the multivariate normal parameters
         MU=[X0(1) X0(2)] : The mean for the multivariate normal pdf
         SIGMA=[X0([3 4]);XO([4 5])] - the covariance matrix for the multivariate normal pdf
         ALPHA = X0(6) - scale factor
         MOD_AMP = X0(7) - scale factor for modulating surround
         MOD_SIGMA = X0(8) - scale factor for SIGMA to determine surround

     ELLIPSE_PARAMS = a list of column vectors; each column describes 1 ellipse
         the first row has the X_Ctr position, the second row has the Y_Ctr
         position, the third row has the X axis vertex, the fourth row has the
         Y axis vertex, and the fifth row has the rotation (in radians)
     XMESH = The X coordinates over which to calculate the response
     YMESH = The Y coordinates over which to calculate the response
   Outputs:
     Y - The response, in a column vector, for each ellipse

   See also: vlt.image.inside_ellipse, MVNPDF