For time integrations of the wave equation, it is desirable to use a scheme that is stable over a wide range of the Courant number. Implicit schemes are examples of such schemes, but they do that job at the expense of global calculation, which becomes an increasingly serious problem as the horizontal resolution becomes higher while covering a large horizontal domain. In this poster, we will show that an explicit space-centered scheme using an infinite number of grid points in space can be made equivalent to the trapezoidal implicit scheme. To avoid global calculation, we will introduce a truncated version of the scheme that uses only a finite number of grid points and examine its stability.