Biquad -- 2nd-order IIR filter using externally provided coefficients
Synopsis
biquad b0 b1 b2 a0 a1 a2
Function
Apply a biquad IIR filter with the given coefficients. Where b
and a are the numerator and denominator coefficients respectively.
See http://en.wikipedia.org/wiki/Digital_biquad_filter (where a0 = 1).