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