Hallo, cristiano figueirÿfffff3 hat gesagt: // cristiano figueirÿfffff3 wrote:
ok, that i understand, i'll make some tests with this value...to modify the default i call the block~ object rigth?
Yes, just use [block~ 8] or so to get less output.
"Complex numbers are just pairs of numbers as well. FFT gives out cartesian coordinates (re = x, im = y) that are connected to phase and magnitude, if you view the latter as the respective polar coordinates for that fft-bin."
So, each pair is one number from real and the respective from imaginary? (the first from real and first from imag. for example?).
In my example, when i first select the frequency "0"(hertz) for my osc~ (who is gonna be analyzed) why this number (-39.604) appears?
real: -39.604 0 0 0 0 0
0 0
0 0 0 0 0 0
0 0
...
imaginary: 0 -0 -0 -0 -0 -0
-0 -0
-0 -0 -0 -0 -0 -0
...
The number is the real part of your first "osc~" with frequency 0, that is: the "DC offset". The first "osc~" of the bank actually would be a "sig~" in Pd: it doesn't change over time because its frequency is 0.
If you would connect a [sig~ 1] to [rfft~] and print it, then you'd get all zeros everywhere except in the first real value, where you'd get the blocksize (like 8 or 64 or so). You don't get 1, because the [rfft~] isn't normalized. If you connect a [sig~ 0.5] you'd get blocksize/2 in the first real bin, and with [sig~ -1] you get -(blocksize).
Using amp = sqrt(re^2 + im^2) you can calculate the amplitude of your signal manually from re and im as well and would get e.g. 8 for [sig~ 1] at [block~ 8] (which is unnormalized again). The phase is arctan(im/re) or arctan(0/bs) = 0, which is okay for a DC signal.
Ciao
Frank Barknecht _ ______footils.org__