This function initializes the arbitrary IIRIIR filter state structure in the external buffer. Before using the
function, compute the size of the external buffer by calling the
function. The initialization functions copy the taps from the
array into the
structure . The
specifies the delay line values. If the
pointer to the array is not
, the array content is copied into the context structure, otherwise the delay values of the state structure are set to values that minimize the start-up and ending transients. These values are obtained by matching the initial conditions to remove the DC offset at the beginning and the end of the input vector.