typedef struct MEIPostfilterSection {
   MEIFilterType    type;
   MEIFilterForm    form;
   struct {
        struct {
            double breakPoint;      /* Hz */
        } lowPass;

        struct {
            double breakPoint;     /* Hz */
        } highPass;

        struct {
            double centerFrequency; /* Hz */
            double bandwidth;       /* Hz */
        } notch;

        struct {
            double centerFrequency; /* Hz */
            double bandwidth;       /* Hz */
            double gain;            /* dB */
        } resonator;

        struct {
            double lowFrequencyGain;    /* dB */
            double highFrequencyGain;   /* dB */
            double centerFrequency;     /* Hz */
        } leadLag;

        struct {
            double a1;
            double a2;
            double b0;
            double b1;
            double b2;
        } biquad;

        struct {
            double a1;
            double a2;
            double b0;
            double b1;
            double b2;
        } digitalBiquad;

        struct {
            long poleCount;
            long zeroCount;
            struct {
                double  real;
                double  imag;
            } pole[2];
            struct {
                double  real;
                double  imag;
            } zero[2];
         } polesZeros;

        struct {
            long poleCount;
            long zeroCount;
            struct {
               double real;
               double imag;
            } pole[2];
            struct {
               double real;
               double imag;
            } zero[2];
         } digitalPolesZeros;

        struct {
            double d1;
            double c1;
            double c2;
            double a2;
            double a1;
            double b1;
        } stateSpaceBiquad;
    } data;
} MEIPostfilterSection;

/*   Set a 4th order low-pass post-filter by using two 
     2nd order low-pass sections.
     Sample usage:   

     returnValue =        
         fourthOrderLowPass(filter, 300 /* Hz */);
*/
long filterFouthOrderLowpass(MPIFilter filter, long breakPointFrequency)
{
    MPIFilterConfig config;    
    MEIPostfilterSection sections[2];    
    long returnValue;    

    section[0].type = MEIFilterTypeLOW_PASS;    
    section[0].form = MEIFilterFormINT_BIQUAD;    
    section[0].lowPass.breakpoint = breakPointFrequency;    
    section[1] = section[0]; /* copy first section */    

    returnValue =        
        meiFilterPostfilterSet(filter, 2, sections);    

    return returnValue;
}