Kleinfeld product
K = kleinfeld(W, X, Y, Z)
K = kleinfeld(W, X, Y, Z) returns (wx, y, z) - x(w, y, z) - (x, y, z)w where (a, b, c) is the associator. The parameters must be octonions. The product has the property that it vanishes if any two of the four parameters are identical in value. Because the associator uses matrix multiplication, this function may give incorrect results if the parameters are not scalar.