现代通信系统（MATLAB版）（第二版） 图1.3 矩形脉冲的各种傅利叶级数的近似

%%%fourier tranform%draw the rect signalclear;x=[-2:0.01:2];y=rect(x);plot(x,y);axis([-2,2,-0.2,1.2]);%draw the fourier serialshold on;%n=3;%z=fourierSerials(x,3);%plot(x,z);%text(0,1,'n=3');for n=1:2:9; z=fourierSerials(x,n); plot(x,z); %text(n,1,num2str(n));endn=0;z=fourierSerials(x,n);plot(x,z);hold off;

 

function [ y ] = rect( x)%UNTITLED Summary of this function goes here% Detailed explanation goes herenum=length(x);i=0;while i<num i=i+1; if(x(i)>=-1 && x(i)<=1) y(i)=1; else y(i)=0; endend;

 

function [ y ] = fourierSerials( x,n)%UNTITLED2 Summary of this function goes here% Detailed explanation goes here m=1; while m<=length(x) sum=1/2; for i=1:n; if(n~=0) sum=sum+sinc(i/2)*cos(2*pi*x(m)*i/4); end; end; y(m)=sum; m=m+1; end;end