Omnidirectional plane-wave destruction |

The above maxflat condition is a linear system with unknown variables . In order to obtain a non-zero solution, we use only the first equations, which zeros the partial derivatives with order less than , and impose an additional constraint on the filter coefficients,

This additional constraint yields a unit amplitude response at zero frequency, similarly to the 1D maxflat approximation (Chen et al., 2013).

2013-08-09