On Oct 30, 2009, at 12:53 AM, Liu Yan wrote:
When I compile the silver dispersion material with my own epsilon-
function using meep, the result shows that there is an error:
"ERROR: In procedure *:
ERROR: Wrong type: #<procedure frequency (x)>"
I specified the epsilon-function as below
"(material-function
(make epsilon-func (- 5 (/ 7.66 (- (* 2 pi frequency 2 pi
frequency) (* i 0.0796 2 pi frequency)))))
)"
What is wrong with this problem? Anyone can help me?
The syntax is
(make material-function (epsilon-func myfunc))
where myfunc is a function of position p that returns the dielectric
constant at that point:
(define (myfunc p) ....do something with p and return epsilon...)
In your code, you aren't using the right syntax in several ways (you
don't use "make" properly, the argument to epsilon-func isn't a
function, etcetera)....but more seriously, it looks like you somehow
got the impression (where?) that epsilon-func allows you to pass an
arbitrary function of *frequency*. This is totally wrong.
Nothing in Meep allows you to specify epsilon as an arbitrary function
of frequency; Meep is a time-domain program, so it can only represent
material dispersion by fitting it to certain forms (Lorentzians
etcetera) that can be implemented as an auxiliary differential
equation (or an IIR filter, for DSP people). See the section of the
manual on materials in Meep.
Steven
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