Re: NEC-LIST: null result

> > I'm attempting to run simulation which includes on the order of 10^2
> > resistive wires. One of those wires is being stimulated by a voltage
> > source, and the frequency is being swept over the range of a few MHz to
> > a little more than !0^2 MHz.
> > NEC appears to begin the simulation and for whatever reason, terminates
> > in less than one second. There is no error message, and the output file
> > is empty.
> > I'm curious if there are:
> > 1. limitations on the number of wires that can be simulated?
> > 2. a minimum spacing that is required between wires? (My shortest
> > spacings are 0.0254 meters between wires with 1mm diameter.)
> > 3. other issues that I may be missing which might cause this behavior?
> > cheers
> > -Billy Robbins
>
>
> Something else is wrong. Do you get the initial startup message?
>
> There's a limit on the number of segments, but it's typically huge
> (you say 100 wires.. is that 100 segments, or 100 wires with many
> segments each). Depending on which version of the program you are
> running, you'll have different limits (since FORTRAN does static
> allocation of the arrays, it's a compile time change).
>
> 1mm wires that are 1cm apart aren't a big deal.
>
> Have you tried downloading and using 4nec2? It comes with the
> standard NEC2 engine and some test cases.
 
The package can be updated to allow more wires and such. The limits
are based on the total number of segments, not wires. In most
compilations, the limits are based on the limits put in for the
specific machine (one of the reasons NEC2 or NEC4 need to be
recompiled for the specific machine). To generalize, the code would
have to be rewritten to allow dynamic allocation, an option
introduced with several compilers and with FORTRAN 90.

Several folks have asked about the speed. That may be an issue on
both speed and limits with Windows compilers. The problem there
becomes the default memory allocation by Windows. Basically Windows
typically retains some memory in reserve for the other applications
that it is assumed you will be using and often uses virtual memory
(disk use) way before you might expect.

My comments may not help much, but may explain some of the limits and
speed issues that folks have been discussing.

Bill

-- 
The NEC-List mailing list
NEC-List_at_robomod.net
http://www.robomod.net/mailman/listinfo/nec-list