RTF_CREATE_BANDPASS_ANALYTIC(3)

💖 RTF_CREATE_BANDPASS_ANALYTIC 💖

okay bestie, welcome to section 3 of the rtfilter library manual, this one's called rtf_create_bandpass_analytic and it's genuinely so cool, let's get into it 🦋

✨ NAME ✨

rtf_create_bandpass_analytic — makes you an IIR filter that estimates the analytic signal in a bandpass. yes, that's the whole job. iconic behaviour tbh 👑

🌸 SYNOPSIS 🌸

#include <rtf_common.h>

hfilter rtf_create_bandpass_analytic(unsigned int nch, int proctype,
                                     double fl, double fh,
                                     unsigned int num_pole);

💅 DESCRIPTION 💅

so like, rtf_create_chebychev() creates an IIR chebychev filter that processes nch channels, and the data type is whatever you told it with proctype. the output of the filter is the analytic signal of the bandpassed data sitting between the normalized frequencies fl and fh. 🎀

and num_pole? that's the number of poles of the Chebychev filter that gets used as the basis of the analytic filter. like, it's the blueprint, fr fr.

quick vibe check on normalized frequencies, because this matters: a normalized frequency is the ratio between the absolute frequency and the sampling frequency — so a value of 1.0 refers to the sampling frequency. periodt. ✨

now the fun technical bit: the Z-transform of this filter has complex coefficients. so, just like rtf_create_filter(3), the filter you create will output complex values, and it keeps the precision you specified with proctype. no cap. 🫶

⚠️ okay listen, this part is important: this filter can quickly become unstable as the number of pole specified increased. 😭 please refers to the authors of the library to know the stability domain (TODO: provides the stability domain here). like, don't just rawdog the pole count and hope for the best, bestie 💀

⭐ RETURN VALUE ⭐

• Returns the handle to the created filter in case of success 💖
• NULL otherwise 🙈

👑 SEE ALSO 👑

• rtf_create_filter(3)
• rtf_destroy_filter(3)

and that's the page!! brought to you by EPFL, dating all the way back to 2010 — vintage but still slaying 💜 go build your filters, you've got this 🌈✨