Why doesnt the Fourier Transformation Work

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dieter alfred 2020-7-16

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https://ww2.mathworks.cn/matlabcentral/answers/566145-why-doesnt-the-fourier-transformation-work

编辑： dieter alfred 2020-7-16

Hello, I programmed a Fourier Transformator. Currently I generate a sine wave and Transform it. Later I want to use Sound. But I dont know how to write the Sound into a vector. But to my Question. If I run the code. I dont get a wave. I just get a Line. But what is the Problem? What is my Mistake?

wave = zeros(1,360)
samplingrate = 360
cyclestart = -100;
cyclesteps = 0.1;
cycleend = 100;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
adder = 0
for a = 1:length(wave)
  wave(a) = 10*sin(a/36);   %%<== only temporarily for generating a wave in the final version I want to read audio into a vector.
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
seconds = length(wave)/samplingrate;
b = 1;
plotx = cyclestart:cyclesteps:cycleend;
ploty = cyclestart:cyclesteps:cycleend;
for i = cyclestart:cyclesteps:cycleend
  centerx = 0;
  centery = 0;
  averagepoint=0
  for c = 1:length(wave)
    centerx = wave(c)*cos(2*pi*i*seconds/length(wave)*c);
    centery = wave(c)*sin(2*pi*i*seconds/length(wave)*c);
    averagepoint = averagepoint + sqrt(centerx*centerx+centery*centery);
  end     
  ploty(b)=averagepoint*length(wave)/samplingrate;
  disp(datestr(now,'HH:MM:SS.FFFFFF')); 
  disp(i);
  b = b + 1;
end
xlabel('Frequency');
plot(plotx,ploty);