Hello,
I recognize negative values after filtering with "ippsFIR_32f_I", although neither my taps (feed forward coefficients) nor the input vector are negative.
How is this possible?
Here is my code snippet, which reproduces this strange behaviour.
Note: If changing "iNumIters" to a smaller value, this behaviour does not occur anymore.
[cpp] // initializations and declarations
IppStatus IppStatus;
IppsFIRState_32f* pState;
int NFilt = 4096;
std::vector b(NFilt, 1.0f/NFilt); // Feed forward coefficients (taps)
std::vector bCheck(NFilt, 0.0f); // vector to check coefficients
std::vector delayLine(NFilt,0.0f); // initial condition
std::vector delayLineCheck(NFilt,0.0f); // vector to check final condition
std::vector x(NFilt+1024, 0.0f); // input signal
for (int k=2; k = k / (float)x.size();
int iNumIters = NFilt + 512;
// process filtering
IppStatus = ippsFIRInitAlloc_32f(&pState, &b[0], NFilt, &delayLine[0]);
IppStatus = ippsFIRGetDlyLine_32f(pState, &delayLineCheck[0]);
IppStatus = ippsFIRGetTaps_32f(pState, &bCheck[0]);
IppStatus = ippsFIR_32f_I(&x[0], iNumIters, pState); // second element becomes negative. Why?
IppStatus = ippsFIRGetDlyLine_32f(pState, &delayLineCheck[0]);
IppStatus = ippsFIRGetTaps_32f(pState, &bCheck[0]);
IppStatus = ippsFIRFree_32f(pState);
[/cpp]
IPP Version: 6.0.0.61
I would be very thankful for any help.
Sincerely yours
