You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mdnerr.m
    path of file: ./repos/bnt/netlab3.3
    
    the code of the file until where you have to start completion: function e = mdnerr(net, x, t)
%MDNERR	Evaluate error function for Mixture Density Network.
%
%	Description
%	 E = MDNERR(NET, X, T) takes a mixture density network data structure
%	NET, a matrix X of input vectors and a matrix T of target vectors,
%	and evaluates the error function E. The error function is the
%	negative log likelihood of the target data under the conditional
%	density given by the mixture model parameterised by the MLP.  Each
%	row of X corresponds to one input vector and each row of T

    
function e = mdnerr(net, x, t)
%MDNERR	Evaluate error function for Mixture Density Network.
%
%	Description
%	 E = MDNERR(NET, X, T) takes a mixture density network data structure
%	NET, a matrix X of input vectors and a matrix T of target vectors,
%	and evaluates the error function E. The error function is the
%	negative log likelihood of the target data under the conditional
%	density given by the mixture model parameterised by the MLP.  Each
%	row of X corresponds to one input vector and each row of T
%	corresponds to one target vector.
%
%	See also
%	MDN, MDNFWD, MDNGRAD
%

%	Copyright (c) Ian T Nabney (1996-2001)
%	David J Evans (1998)

% Check arguments for consistency
errstring = consist(net, 'mdn', x, t);
if ~isempty(errstring)
  error(errstring);
end