Christos Koukouvinos and Marilena Mitrouli have computed the GEP for some of 
the 487 inequivalent Hadamard matrices of order 28 on Neil Sloane's web page 
which were constructed by Kimura:


 Had.28.18
 Automorphism group has order = 18 = 2 * 3^2

 ps=(1, 2, 2, 4, 3, 10/3, 18/5, 4, 4, 5, 74/15, 508/111, 5.937, 5.069,
    5.912, 5.447, 5.8408, 5.557, 6.4615, 28/3, 28/8, 28/4, 28/4, 28/2,
    28/4, 28/2, 28/2, 28)

 Had.28.34
 Automorphism group has order = 2

 ps=(1, 2, 2, 4, 3, 10/3, 18/5, 4, 38/9, 4.5789, 5.1954, 5.4159, 4.9804,
    4.7323, 5.9634, 5.25, 35/6, 8.4, 28/6, 28/3, 28/8, 28/4, 28/4,
    28/2, 28/4, 28/2, 28/2, 28)

All 487 matrices have the same SNF: 1,2^{13,14^{13},28.

This page was created on 27th Novemeber 1999.