A D-optimal matrix of order 
is an 
(-1,1)-matrix attaining
the Ehlich-Wojtas determinant bound
 |
for 
(Ehlich 1964, Wojtas 1964). Such a matrix solves Hadamard's
maximum determinant problem for that order.
Georgiou and Stylianou (2026) constructed a D-optimal matrix of order 198 with determinant of absolute value 
. Their construction uses two subsets
of 
of sizes 43 and 42 whose combined ordered nonzero difference multiplicities are all
36.
