calculates the circular correlation of two real vectors of period iSize.
int fft_fft_correlation( int iSize, double * vSig1, double * vSig2 )
Returns 0 for success or error codes for failure.
//Assume the current Worksheet has 4 columns, the first two columns contain 2 sets of real
//data values. This piece of code computes the circular correlation of two real vectors.
//The result is output into the third column, and it's Fourier transform is in the
int n=8, success;
Worksheet wks = Project.ActiveLayer();
Dataset xx(wks, 0);
Dataset yy(wks, 1);
Dataset aa(wks, 2);
Dataset bb(wks, 3);
vector x = xx;
vector y = yy;
success = fft_fft_correlation(n, x, y);
aa = x;
bb = y;