Hello all, I used the matlab to do the fourier transformation, but I found the result (the plotting of the spectrum space) is different from what the textbook tells us. t=[0:100]; for time series f1=50; f2=100; for two frequences f=linspace(-f2, f2, length(t)); for frequence series y=sin(2*pi*f1*t) + sin(2*pi*f2*t); because y comes from the combination of two-different-frequence sin function, so the specturm of y should only have two point (f1 and f2) are non-zero. yy=fft(y); plot(f, yy); we should get a plotting like ^ | | | | | | | |________________>f 0 f1 f2 but unforunately, what I get is a continuous curve somewhat nlike a random noise. Please help! Rex

It is not obvious how you are using this in a game, and it looks more complex than you need for any game simulation. If you can provide some details of what this is being used for there is probably a better solution using more straightforward maths.

Yeah, I''m closing this topic. The fact that the question even included the phrase "result [...] is different from what the textbook tells us" makes it certain that this is related to a homework assignment. Read the forum FAQ. Its time to collaborate with students at your school or your teacher/professor.

Graham Rhodes
Senior Scientist
Applied Research Associates, Inc.