Suppose that a parameter y= 123.(adsbygoogle = window.adsbygoogle || []).push({});

That parameter is somehow "perturbed" and its instantaneous value is:

y(t)= 123 +

sin(t - 50°) * 9 +

sin(t * 3 + 10°) * 3 +

sin(t * 20 + 60°) * 4

Suppose that I don't know the above formula, but I can calculate y(t) for any t. Hence I decide to use the Fourier transform to infer all the y's components.

If I use a sufficient number of samples to calculate y(t) (I currently use 2^{16}samples) for 0 ≤ t ≤ 2π, I obtain:

y(t)= 122.999955606783 +

sin(t - 49.9942506502916°) * 8.99994072213981 +

sin(t * 3 + 10.0193463603278°) * 2.9999458244411 +

sin(t * 20 + 60.11052441823°) * 4.00000160503959

which is a very good result, while if I try to calculate y(t) for arbitrary t, I obtain a totally meaningless result.

Please, could somebody help me?

Thank you

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# I Fourier transform

Have something to add?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**