double sample_covariance(double A[], double B[], int length)
// Function calculates the sample covariance the array A and array B, whose lengths are "length"
{
double meanA = mean_value(A, length);
double meanB = mean_value(B, length);
double SOS = 0;
for (int i=0; i<length; i++)
{ SOS += (A[i] - meanA) * (B[i] - meanB); }
return double sample_cov = SOS / length;
}

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