## FIgdelIIR

#### Routine

double FIgdelIIR (double w, const float h[][5], int Nsec)

#### Purpose

Calculate the group delay for a cascade IIR filter

#### Description

This function calculates the group delay of an IIR filter specified by its coefficients. The filter is a cascade of second order sections, with the z-transform of the i'th filter section given as

               h(i,0)*z^2 + h(i,1)*z + h(i,2)
      H(i,z) = ------------------------------ .
                  z^2 + h(i,3)*z + h(i,4)

The group delay in seconds at frequency f for a filter with sampling frequency Fs can be calculated as

      gdelay = FIgdelIIR (2.0 * Pi * f / Fs, h, Nsec) / Fs  .

#### Parameters

-> double w
  Normalized radian frequency (0 to Pi).
-> const float h[][5]
  Array of filter coefficients for the filter sections. Each filter section is defined by 5 filter coefficients.
-> int Nsec
  Number of filter sections

#### Author / revision

P. Kabal / Revision 1.6 2003/05/09

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