// output of ./demo/comb/conference-quadres-demo.cc: // Description: //% Conference and Hadamard matrices by quadratic residues Argument q must an odd prime. A QxQ conference matrix will be computed where Q=q+1. A NxN Hadamard matrix will create where N=q+1 if q%4==1, N=2*(q+1) if q%4=3. Optional: more odd primes for more matrices. Quadratic characters modulo 11: 0 + - + + + - - - + - 12x12 conference matrix C: 0 + + + + + + + + + + + - 0 + - + + + - - - + - - - 0 + - + + + - - - + - + - 0 + - + + + - - - - - + - 0 + - + + + - - - - - + - 0 + - + + + - - - - - + - 0 + - + + + - + - - - + - 0 + - + + - + + - - - + - 0 + - + - + + + - - - + - 0 + - - - + + + - - - + - 0 + - + - + + + - - - + - 0 12x12 Hadamard matrix H: + + + + + + + + + + + + - + + - + + + - - - + - - - + + - + + + - - - + - + - + + - + + + - - - - - + - + + - + + + - - - - - + - + + - + + + - - - - - + - + + - + + + - + - - - + - + + - + + - + + - - - + - + + - + - + + + - - - + - + + - - - + + + - - - + - + + - + - + + + - - - + - + Quadratic characters modulo 5: 0 + - - + 6x6 conference matrix C: 0 + + + + + + 0 + - - + + + 0 + - - + - + 0 + - + - - + 0 + + + - - + 0 12x12 Hadamard matrix H: + + + + + + - + + + + + + + + - - + + - + - - + + + + + - - + + - + - - + - + + + - + - + - + - + - - + + + + - - + - + + + - - + + + + - - + - - + + + + + - - - - - - + - + - - + - - - + + - + + - + - - - - - - + + + - + - + - - + - - - + + - - + - + - + + - - - + + - - + - - - + + - -