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: vl_impattern.m
    path of file: ./repos/panorama/lib/vlfeat-0.9.20/toolbox/imop
    
    the code of the file until where you have to start completion: function im = vl_impattern(varargin)
% VL_IMPATTERN Generate an image from a stock pattern
%   IM=VLPATTERN(NAME) returns an instance of the specified
%   pattern. These stock patterns are useful for testing algoirthms.
%
%   All gene
    
function im = blob(args)
[u,v,opts,args] = commonOpts(args) ;
opts.sigma = 0.15 ;
opts.anisotropy = .5 ;
opts.orientation = 2/3 * pi  ;
opts.cut = false ;
opts = vl_argparse(opts, args) ;
im = zeros(size(u)) ;
th = opts.orientation ;
R = [cos(th) -sin(th) ; sin(th) cos(th)] ;
A = opts.sigma * R * diag([opts.anisotropy 1]) ;
T = [0;0] ;
[x,y] = vl_waffine(inv(A),-inv(A)*T,u,v) ;
im = exp(-0.5 *(x.^2 + y.^2)) ;
if opts.cut
  im = im .* double(x > 0) ;
end