# 70×70 {-1, +1} matrices of largest known determinant

|Det Rj| = 46534198660232702315328376954951333913138372×269 = 1156×1733×269

Ratio of |Det Rj| to Ehlich/Wojtas bound: 0.985507

M=RjTRj= Rj RjT:

Rj:
The matrices of have the form

``` | X   J   K |
|           |
|  T        |
| J   A   B |
|           |
|  T   T   T|
| K  -B   A |
```
where X is an arbitrary 2×2 matrix, J is a 2×34 matrix of 1s, K is a 2×34 matrix of the form
``` ++++++...+
------...-
```
and A and B are 34×34 circulant matrices.

There are many choices for the first rows of A and B, of which one example is given:
a1, b1:

```+++++++-+-+-+-++---+--++--+--+----
+-+-++----+---++++--+-++-++---+++-
```

Notes:

1. Cannot achieve Ehlich/Wojtas bound since 69=70-1 is not the sum of two squares.
2. This form has not been proved to be optimal.
3. This determinant was discovered by Will Orrick and Tomas Rokicki in April 2005; it surpasses an old record.

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Page created 3 October 2012.