22 Jul
2011
22 Jul
'11
6:38 p.m.
Nice one. Interestingly, a paper published only this year proves that if an NxN Hadamard matrices is also a circulant -- like Rich's matrix -- then N is 1 or 4. See < http://blms.oxfordjournals.org/content/early/2011/01/24/blms.bdq112.full.pdf >. --Dan ----- Rich wrote: << How about recasting as - + + + + - + + + + - + + + + - for "obvious" symmetry? To go from your reverse-quaternion-sign matrix to mine, negate the first column and the last three rows; then swap rows 2 & 4.
Sometimes the brain has a mind of its own.