inverse FIR filter

design inverse filter (FIR) from mono or stereo impulse response

[ih]=invFIR(type,h,Nfft,Noct,L,range,reg,window)
- optional GUI included-

inputs overview
---------------
type:
1. 'linphase': symmetric two-sided response compensating magnitude while maintaining original phase information
2. 'minphase': one-sided response compensating magnitude with minimal possible group delay
3. 'complex': asymmetric two-sided response compensating magnitude and phase

h:
mono or stereo impulse response (column vector)

Nfft:
FFT length for calculating inverse FIR

Noct:
optional fractional octave smoothing (e.g. Noct=3 => 1/3 octave smooth, Noct=0 => no smoothing)

L:
length of inverse filter (truncates Nfft-length filter to L)

range:
frequency range to be regulated (e.g. [32 16000] => 32 Hz to 16 kHz)
%
% reg:
amount of regularization (in dB) inside (reg(1)) and outside (reg(2)) the specified range (example: reg=[20 -6] => inverts frequency components within 'range' with a max. gain of 20 dB,
while dampening frequencies outside 'range' by 6 dB)

window:
window=1 applies a hanning window to the inverse filter