L18_A
Fourier transform to solve diffusion equations
Aperiodic initial condition
Inverse Fourier Transform

L18_B
Comments of initial condition:
1. initial condition is constant: error function
2. Diffusion, smoothing, homogeneous process
    EX: MOSFET
3. Initial condition multiply with Gaussian function
4. Initial condition is delta function
    Ex:Ion implantation