Periodic-soliton solutions of the (2+1)-dimensional Kadomtsev--Petviashvili equation

2N line-soliton solutions of the (2+1)-dimensional Kadomtsev--Petviashvili equation can be presented by resorting to the Hirota bilinear method. By extending the real parameters into complex parameters, this paper obtains N periodic-soliton solutions of the (2+1)-dimensional Kadomtsev--Petviashvili equation from the 2N line-soliton solutions.