In reply to srinivas.emb27:
You can write this as
for(i=0; i<=11;i++) begin
file_data_re0[i*12 +: 12] = data_re0;
file_data_im0[i*12 +: 12] = data_im0;
end
or simply
file_data_re0 = {12{data_re0}};
file_data_im0 = {12{data_im0}};