%
% Window function sim
%      http://okawa-denshi.jp/
%      (c)A.Okawa
%
i=sqrt(-1);
PAI=3.141592;
dt=0.03;
dw=0.05;
ws=2;
we=8;

% Param
T=10;
w0=5;
v=1;
t=[-T:dt:T];

n=length(-T:dt:T);
%f=v*ones(1,n);
%f=v*cos(w0*t);
f=v*sin(w0*t);

w=[ws:dw:we];
m=length(ws:dw:we);
Fw_r=zeros(1,m);
Fw_hn=zeros(1,m);
Fw_hm=zeros(1,m);
Fw_fl=zeros(1,m);

% Rectangle
rec=ones(1,n);
% Hanning
han=0.5+0.5*cos(PAI*t/T);
% Hamming
ham=0.54+0.46*cos(PAI*t/T);
% Flattop
fla_1=sinc(2*PAI*t/T);
fla=ham.*fla_1;

ft_re=f.*rec;
ft_hn=f.*han;
ft_hm=f.*ham;
ft_fl=f.*fla;

%plot(t,ft_hn,t,ft_hm,t,ft_fl)

% Fourier sekibun
for j=1:m-1
    fe=exp((-1)*i*w(j)*t);
    ft_re2=ft_re.*fe;
    ft_hn2=ft_hn.*fe;
    ft_hm2=ft_hm.*fe;
    ft_fl2=ft_fl.*fe;
%
    for k=2:n-1
        Fw_r(j)=Fw_r(j)+ft_re2(k);
        Fw_hn(j)=Fw_hn(j)+ft_hn2(k);
        Fw_hm(j)=Fw_hm(j)+ft_hm2(k);
        Fw_fl(j)=Fw_fl(j)+ft_fl2(k);
    end
    Fw_r(j)=dt*(Fw_r(j)+0.5*ft_re2(1)+0.5*ft_re2(n));
    Fw_hn(j)=dt*(Fw_hn(j)+0.5*ft_hn2(1)+0.5*ft_hn2(n));
    Fw_hm(j)=dt*(Fw_hm(j)+0.5*ft_hm2(1)+0.5*ft_hm2(n));
    Fw_fl(j)=dt*(Fw_fl(j)+0.5*ft_fl2(1)+0.5*ft_fl2(n));
%
end

plot(w,Fw_r*i,w,Fw_hn*i,w,Fw_fl*i)
%plot(w,Fw_r,w,Fw_hn,w,Fw_fl)