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: spm_smoothkern.m
    path of file: ./repos/bspm/thirdparty/spm12
    
    the code of the file until where you have to start completion: function krn = spm_smoothkern(fwhm,x,t)
% Generate a Gaussian smoothing kernel
% FORMAT krn = spm_smoothkern(fwhm,x,t)
% fwhm - full width at half maximum
% x    - position
% t    - either 0 (nearest neighbour) or 1 (linear).
%        [Default: 1]
%
% krn  - value of kernel at position x
%__________________________________________________________________________
%
% For smoothing images, one should really convolve a Gaussian with a sinc
% function. For smoothing histograms, the kernel should be a Gaussian
% convolved with the histogram basis function used. This function returns
% a Gaussian convolved with a triangular (1st degree B-spline) basis 
% function (by default). A Gaussian convolved with a hat function (0th 
% degree B-spline) can also be returned.
%__________________________________________________________________________
% Copyright (C) 2005-2011 Wellcome Trust Centre for Neuroimaging


    
function krn = spm_smoothkern(fwhm,x,t)
% Generate a Gaussian smoothing kernel
% FORMAT krn = spm_smoothkern(fwhm,x,t)
% fwhm - full width at half maximum
% x    - position
% t    - either 0 (nearest neighbour) or 1 (linear).
%        [Default: 1]
%
% krn  - value of kernel at position x
%__________________________________________________________________________
%
% For smoothing images, one should really convolve a Gaussian with a sinc
% function. For smoothing histograms, the kernel should be a Gaussian
% convolved with the histogram basis function used. This function returns
% a Gaussian convolved with a triangular (1st degree B-spline) basis 
% function (by default). A Gaussian convolved with a hat function (0th 
% degree B-spline) can also be returned.
%__________________________________________________________________________
% Copyright (C) 2005-2011 Wellcome Trust Centre for Neuroimaging

% John Ashburner
% $Id: spm_smoothkern.m 4419 2011-08-03 18:42:35Z guillaume $


if nargin<3, t = 1; end