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: fevalt.m
    path of file: ./repos/chebfun/@chebfun3
    
    the code of the file until where you have to start completion: function W = fevalt(f, x, y, z)
%FEVALT   Evaluate a CHEBFUN3.
%   W = FEVALT(F, X, Y, Z) returns a tensor of values W of size 
%   length(X)-by-length(Y)-by-length(Z). X, Y and Z should be vectors of 
%   doubles. This is equivalent to fist constructing
%   [X,Y,Z] = NDGRID(X,Y,Z) and then computing W = FEVAL(F, X, Y, Z).
%   
%   FEVALT is different from W = FEVAL(F, X, Y, Z) which creates a
%   vector W while W = FEVALT(F, X, Y, Z) returns W as a tensor.
%
% See also CHEBFUN3/FEVAL.

    
function W = fevalt(f, x, y, z)
%FEVALT   Evaluate a CHEBFUN3.
%   W = FEVALT(F, X, Y, Z) returns a tensor of values W of size 
%   length(X)-by-length(Y)-by-length(Z). X, Y and Z should be vectors of 
%   doubles. This is equivalent to fist constructing
%   [X,Y,Z] = NDGRID(X,Y,Z) and then computing W = FEVAL(F, X, Y, Z).
%   
%   FEVALT is different from W = FEVAL(F, X, Y, Z) which creates a
%   vector W while W = FEVALT(F, X, Y, Z) returns W as a tensor.
%
% See also CHEBFUN3/FEVAL.

% Copyright 2017 by The University of Oxford and The Chebfun Developers.
% See http://www.chebfun.org/ for Chebfun information.

if ( isempty(f) )
    W = {[]}; 
    return
end