The conjugate-gradient nonuniform fast Fourier transform (CG-NUFFT) method for one- and two-dimensional media

The conjugate-gradient fast Fourier transform (CG-FFT) method has been widely used to solve integral equations in electromagnetic wave propagation and scattering problems. A novel method combining the conjugate-gradient and nonuniform fast Fourier transform (CG-NUFFT) algorithms for solving integral equation in electromagnetics is presented. The CG-NUFPT method has been applied to one- and two-dimensional inhomogeneous media. Numerical results show the advantages of the CG-NUFFT method over the CG-FFT method for problems with both electrically large and small regions.