
Calculates Sums of Squares and Cross Products (SSCP) from the selected TableOfReal.
The sums of squares and cross products s_{ij} between the elements of columns i and j are calculated as:
s_{ij} = Σ_{k} (x_{ki}  x̄_{i})(x_{kj}  x̄_{j}), 
where x_{mn} is the element m in column n, and x̄_{n} is the mean of column n.
© djmw 19990218