This routine was meant to be used as a tool to represent the a complex electric field in a plane (with phase and amplitude)
Plots the phase of a 2D complex array (FIELD) in a continuous color scale (hue) and represents the normalized amplitude as brightness (r+g+b)*amplitude.
If AMP = 0 the amplitude is not plotted
If FLAG = 1 the function creates a figure with a dial scale (from 0 to 2*pi) and radial brightness (from 0 to one)
A=PHPLOT(...) creates a 3D uint8 array that can be saved as an image with the syntax IMWRITE(A,'filename','fmt').