' calculates the determinant of Corr-Matrix of the x-vectors
' corr-matrix is (here) a 4x4 matrix 
' given the data x1 x2 x3 x4
' X = (x1 ... x4)

' replace x1 ... x4 by the series names to be considered
group grpx x1 x2 x3 x4

matrix x = @convert(grpx)
scalar det = @det( @cor(x) )

' #det is stored in the worfile