7×7 {-1, +1} matrix of maximal determinant

|Det R| = 9×26 = 9×11×26

Ratio of |Det R| to Ehlich bound: 0.981981

M=RTR=R RT:

 7  3 -1 -1 -1 -1 -1
 3  7 -1 -1 -1 -1 -1
-1 -1  7  3 -1 -1 -1
-1 -1  3  7 -1 -1 -1
-1 -1 -1 -1  7  3 -1
-1 -1 -1 -1  3  7 -1
-1 -1 -1 -1 -1 -1  7

R:

-+++---
+-++---
++---+-
++--+--
---+++-
--+-++-
------+

Notes:

  1. Ehlich bound is not achievable as it is not an integer.
  2. M has block form.
  3. First reported by Williamson [Wi].
  4. R is unique up to equivalence [Wi].

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    Page created 26 January 2002.
    Last modified 18 June 2003.
    Comments: maxdet@indiana.edu