Steven G. Johnson wrote:
On Mon, 4 Sep 2006, Andrea Locatelli wrote:
I have some problems to understand how to manipulate fields at each
time step. For example, I'm doing a 2D TM simulation, and I want to
make some processing on Ez in order to calculate the time-averaged
|Ez|^2. I need to define an auxiliary variable, and at each time step
I should add the calculated |Ez|^2 to this auxiliary variable, and
finally I should output the result. I think I should use the
(before-time T step-function) command, but I have many doubts on how
to define the proper step function, and in particular how I can define
and manipulate "field" variables. Do you have any examples on this topic?
You can get the value of the field just by calling get-field, as
described in the manual. Here is a quick example (hopefully with no
typos) of computing the average |Ez|^2 over 100 time units.
(define Ezsum 0)
(define (do-Ez-sum)
(set! Ezsum (+ Ezsum (sqr (magnitude
(get-field Ez (vector3 0 0 0)))))))
(run-until 100 do-Ez-sum)
(print "the mean |Ez|^2 at (0,0,0) = "
(* Ezsum (/ (meep-fields-dt-get fields) 100))
"\n")
Cordially,
Steven G. Johnson
Thank you for the useful hint... The script works well for a single
point, but I'm wondering if it is possible to make the same operation on
the whole field structure, i.e. I have at each time step the 2D Ez
field, and it would be great if I could have at the end of the
simulation the 2D time-averaged |Ez|^2
Andrea
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