Re: E-field plots

On Thu, 24 May 2007, Jim Andrews wrote:
> I am trying to work through the defect1dsol.ctl example that is posted
> on the nanophotonics course website in order to recreate the figure 4
> that appears there and I am finding that I don't know how to get a
> line plot of Ez from the h5 files.

You can make line plots (or any other kind of plots) from h5 files just by 
reading it into a plotting program.  In Matlab, you can use the hd5read 
command to read an hdf5 file directly; see the examples in:
 	http://www-math.mit.edu/~stevenj/18.369/mpb-demo.pdf
For other programs, you can use h5totxt (part of h5utils) to convert an 
hdf5 file into comma-delimited text.

> I'm having trouble even getting the condition satisfied that the 
> frequency of one of the bands is within the range of the minimum and 
> maximum frequencies of the structure without the defect.  Also, I'm not 
> sure why the minimum and maximum frequencies are defined by use of the 
> following because I don't know what car and cadr mean here (though I can 
> see that this gives the frequencies previously found for the two band 
> case:
> (define gap-min (car freqs))
> (define gap-max (cadr freqs))

car and cadr are two basic Scheme/Lisp primitives, that are documented in 
any Scheme manual.

Given a list L, (car L) returns the first element of the list, and (cdr L) 
returns a list of the elements after the first.  (cadr L) is a standard
abbreviation for (car (cdr L)), i.e. it returns the second element of the 
list. Therefore in the commands above, gap-min and gap-max are set to the 
first and second elements of the freqs list, respectively, because the gap 
in this case is between the first and second bands.

Steven