Environment

GeForce GTX 1070 (8GB)
ASRock Z170M Pro4S [Intel Z170chipset]
Ubuntu 14.04 LTS desktop amd64
TensorFlow v0.11
cuDNN v5.1 for Linux
CUDA v8.0
Python 2.7.6
IPython 5.1.0 -- An enhanced Interactive Python.
gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4
GNU bash, version 4.3.8(1)-release (x86_64-pc-linux-gnu)

This article is related to ADDA (light scattering simulator based on the discrete dipole approximation).

Excerpt from manual.pdf (last revised: February 20, 2014) related to read the internal fields.

Related: ADDA > runtime parameter > -store_int_field / -store_dip_pol > store internal fields and dipole polarizations

-init_field read ...

If you want to input the field to be used as a first guess by the iterative solver, you may try
-init_field read ...
This option was added specifically to facilitate external hacks for the iterative solver.

@ manual.pdf > 12.1 Iterative solver

There are several options to choose the initial field, set by the command line option

-init_field {auto|inc|read <filenameY> [<filenameX>]|wkb|zero}

where zero vector is a general approach and inc (derived from the incident field, more precisely – equal to the right-hand-side of the linear system) may be closer to the exact solution for small index-matching particles.

wkb is derived from the incident field corrected for phase shift during propagation in the particle (Wentzel–Kramers–Brillouin approximation [73]). It can be considered as an extension of inc , but currently it works only for default incident beam – plane wave propagating along the z-axis in particle reference frame (§9) and
not in the surface mode (§7).

...

It is important to note, that ...
In particular, “ -beam read fY fX –init_field inc ” is not completely equivalent to “ -init_field read fY fX ” in terms of the starting vector.