vDSP_deq22

Declaration

void vDSP_deq22(const float *__A, vDSP_Stride __IA, const float *__B, float *__C, vDSP_Stride __IC, vDSP_Length __N);

Parameters

• __A:

  The single-precision real input vector.

• __IA:

  The stride for input vector A.

• __B:

  Five single-precision input filter coefficients, with a stride of one.

• __C:

  The single-precision real output vector.

• __IC:

  The stride for output vector C.

• __N:

  The number of new output elements to produce.

Discussion

This function creates N new values in output vector C, beginning at the third element. The function performs two-pole, two-zero recursive filtering on input vector A, which must contain at least N + 2 values; C must also contain at least N + 2 values. Since the computation is recursive, prior to calling this function, initialize the first two elements in C.

You can only implement this function out of place — that is, the input and output memory must not overlap.

This function performs the following operation:

or (n = 2; n < N+2; ++n) 
    C[n] =
        + A[n-0]*B[0]
        + A[n-1]*B[1]
        + A[n-2]*B[2]
        - C[n-1]*B[3]
        - C[n-2]*B[4];