sql cross join and multiple join code improvement

Question

I am wondering if there is a better way to do this sql query it envolves multiple cross join and joins?

I have 3 tables, and want to compute cardinal product:

table N:
    N
    -
    4

table sums:
    i   S
    -----------
    1   22
    2   26
    3   22


table mults:
    i   j   M
    -------------------
    1   1   122
    1   2   144
    1   3   119
    2   1   144
    2   2   170
    2   3   141
    3   1   119
    3   2   141
    3   3   126

so here is a fiddle

SELECT  ((N.n*M1.m)-(S1.s*S2.s)) / (SQRT((N.n*M2.m)-(pow(S1.s,2))) * SQRT((N.n*M3.m)-(pow(S2.s,2))))
FROM N
CROSS JOIN sums as S1
CROSS JOIN sums as S2
JOIN mults as M1
     ON M1.i = S1.i
     AND M1.j = S2.i
JOIN mults as M2
     ON M2.i = S1.i
     AND M2.j = S1.i
JOIN mults as M3
     ON M3.i = S2.i
     AND M3.j = S2.i;