search for: acbd

...nt indices a and b, and similarly D_{cd} = X_c – X_d, and make a quadratic form D’_{ab}D_{cd} = A_{abcd}, say. Please note that, here a is unequal b, c is unequal d, a is unequal c, b is unequal d. By slightly shuffling the same set of vectors, I generate two other similar quadratic forms, say A_{acbd} and A_{adcb}, where the indices are again as unequal as stated above. In the R-code (a part of ) below, I compute these three forms using pata, patb, patc, respectively, using kronecker products. But from the final result of this code I get the feeling there is a difference between what I want...