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_wft.m
    path of file: ./repos/spm
    
    the code of the file until where you have to start completion: function [C] = spm_wft(s,k,n)
% Windowed fourier wavelet transform (time-frequency analysis)
% FORMAT [C] = spm_wft(s,k,n)
% s      - (t X n) time-series
% k      - Frequencies (cycles per window)
% n      - window length
% C      - (w X t X n) coefficients (complex)
%__________________________________________________________________________

% Karl Friston
% Copyright (C) 2006-2022 Wellcome Centre for Human Neuroimaging


% window function (Hanning)

    
function [C] = spm_wft(s,k,n)
% Windowed fourier wavelet transform (time-frequency analysis)
% FORMAT [C] = spm_wft(s,k,n)
% s      - (t X n) time-series
% k      - Frequencies (cycles per window)
% n      - window length
% C      - (w X t X n) coefficients (complex)
%__________________________________________________________________________

% Karl Friston
% Copyright (C) 2006-2022 Wellcome Centre for Human Neuroimaging


% window function (Hanning)
%--------------------------------------------------------------------------
[T,N] = size(s);
n     = round(n);
h     = 0.5*(1 - cos(2*pi*(1:n)/(n + 1)));
h     = h'/sum(h);
C     = zeros(length(k),T,N);


% spectral density
%--------------------------------------------------------------------------
for i = 1:length(k)
    W     = exp(-1j*(2*pi*k(i)*(0:(T - 1))/n))';
    for j = 1:N
        w        = conv(full(s(:,j)).*W,h);
        C(i,:,j) = w((1:T) + n/2);
    end