slow graph building when d value if big

[madnavs]

In the file model_rn.py, can we have a better way to implement this double for loop? to speedup graph generation.

for i in range(d*d):
                   o_i = conv_4[:, int(i / d), int(i % d), :]
                   o_i = concat_coor(o_i, i, d)
                   for j in range(d*d):
                       o_j = conv_4[:, int(j / d), int(j % d), :]
                       o_j = concat_coor(o_j, j, d)
                       if i == 0 and j == 0:
                           g_i_j = g_theta(o_i, o_j, q, reuse=False)
                       else:
                           g_i_j = g_theta(o_i, o_j, q, reuse=True)
                       all_g.append(g_i_j)