Filter out those frequency components in original data, whose power are greater than threshold.
int fft_threshold_filtering( int iSize, double * vSignal, double dThreshold )
Returns 0 for success or error codes for failure.
//Assume the current Worksheet exists and has 2 columns. The first column contains the
//data to be filtered, the second column contains the result.
int n=256, success;
Worksheet wks = Project.ActiveLayer();
Dataset xx(wks, 0);
Dataset aa(wks, 1);
vector x = xx;
success = fft_threshold_filtering(n, x, dThreshold);
aa = x;