{{b[1], b[2], b[2], b[3]}, {-b[1], (-b[1] + b[3])/2, (b[2] + b[3])/2, (b[1] + 3*b[2])/2}, {-b[2], -b[2], b[2] + b[3], b[1] + b[2]}, {-b[3], (b[1] - b[3])/2, (b[1] + b[2])/2, (3*b[2] + b[3])/2}, {(-b[2] - b[3])/2, (-b[1] - b[2])/2, (-2*b[1] + b[2] + b[3])/2, (b[1] + b[2] - 2*b[3])/2}, {(-3*b[2] - b[3])/2, b[1] - b[2]/2 - b[3]/2, (b[2] - b[3])/2, (b[2] - b[3])/2}, {(-b[1] - 3*b[2])/2, -1/2*b[1] - b[2]/2 + b[3], (-b[1] + b[2])/2, (-b[1] + b[2])/2}, {-b[2] - b[3], (-b[2] + b[3])/2, (-b[2] + b[3])/2, b[1] - b[3]}, {-b[1] - b[2], (b[1] - b[2])/2, (b[1] - b[2])/2, -b[1] + b[3]}}