nec2c core which it uses for reading input files and calculating output data,
but it does not need and indeed does not produce an output file by default.
Graphs of frequency-related data and the current or charge distribution
evolve as the frequency loop progresses, and radiation patterns (far and
near field) are sequentially drawn for each frequency step.
PR: ports/190815
Submitted by: shurd@FreeBSD.org
Approved by: db, skreuzer (mentors)
