izero             121 libavfilter/af_superequalizer.c     return izero(s, alpha(s->aa) * sqrtf(1 - 4 * n * n / ((N - 1) * (N - 1)))) / s->iza;
izero             158 libavfilter/af_superequalizer.c     s->iza = izero(s, alpha(s->aa));