fftmain.m

matlab实现fft,以及ifft算法,包含蝶型运算等文件

t=0:2*pi/16:2*pi-2*pi/16;
data1=sin(t);
y=fftfunction(data1);
y=ifftfunction(y);%作反变换
Pyy = y.* conj(y) / 16;
f = 2*pi*(0:8)/16;
subplot(2,2,1);
stem(f,Pyy(1:9));
data2=[1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0];
y=fftfunction(data2);
y3=ifftfunction(y)
Pyy = y3.* conj(y3) / 16;
f = 1000*(0:8)/16;
subplot(2,2,2);
stem(f,Pyy(1:9));
data31=0.02:0.02:(8*0.02);
data32=(7*0.02):-0.02:0;
data3=[data31,data32];
y=fftfunction(data3);
y2=ifftfunction(y)
Pyy = y2.* conj(y2) / 16;
f = 1000*(0:8)/16;
%f1=0:length(data3)-1;
subplot(2,2,3);
stem(f,Pyy(1:9));