This study presents a numerical convolution representation of a potential induced from a disk of surface density, which has often been investigated in the center region of galaxies. The advantage of this representation is to release the softening length for theN-body method and artificial boundary conditions for the spectral methods. With the help of fast Fourier transform, the computational complexity is onlyO(M2(log2⁡M)), whereMis the number of zones in one dimension. Numerical results show

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... almost second order of accuracy on a Cartesian coordinate system. A comparison study also demonstrates that this method can calculate the potential for disk surface density based on the uniform grids.