非线性光学光线追迹，采用了分步傅里叶变换。注释为西班牙文-Nonlinear optical ray tracing, using the split-step Fourier transform. Notes in Spanish

The fft.c file is C code for a function to compute the 16 point real Fast Fourier Transform using the split radix algorithm. -The fft.c file is C code for a function to compute the 16 point real Fast Fourier Transform using the split radix algorithm.