Dear David, Am Sonntag, den 19.07.2009, 16:21 +0200 schrieb David Bateman: > Søren Hauberg wrote: > > Hi > > > > tor, 16 07 2009 kl. 17:34 +0200, skrev Christian Neumair: > > > >> the attached patch fixes qamdemod(). Its purpose is to provide a > >> nearest-neighbour quantizer against a pre-defined set of points (called > >> QAM signal space constellations). > >> > > > > This patch looks good to me, so I applied it. > > (...) > qammod and qamdemod need to be reworked to allow 8QAM, 32QAM, etc which > are non-symmetric gray mappings. The qaskenco and qaskdeco function > already have this but are superceded in matlab by qammod and qamdemod, > so it would make sense to make these call the same underlying code. The > versions in qaskenco and qaskdeco were fairly well optimized at the time > I wrote them so this code might serve as a basis, but it probably makes > sense to check that the same gray mappings are used in the matlab > versions of qaskenco and qammod before doing this.. See the thread > > http://www.nabble.com/qammod-proposed-update-to24420799.html > > that proposed some code as well.
Thank you for the link. Comparing qaskenco() from MATLAB R2008 / 7.7.0.471 and the code written by you (octave 3.0.1), it looks like a) MATLAB's version *always* returns column vectors while octave's automatically returns row vectors if nargin==1 and otherwise adapts to the orientation of the input vector b) for only one return argument, MATLAB returns only the in-phase component while octave's returns both as complex number In both cases, I prefer octave's implementation but these differences should be documented somewhere. c) none of them can handle multidimensional input arguments which wonders me because that's the way I always want to use them for large simulation setups. IMO this kind of operation should just work entry-wise. d) the Gray coding is very different. In general, how should we handle such tiny incompatibilities between MATLAB and octave? Where should they be documented? Shouldn't there be a website and doc page listing the differences package-wise? best regards, Christian Neumair -- Christian Neumair <cneum...@gnome.org> ------------------------------------------------------------------------------ Enter the BlackBerry Developer Challenge This is your chance to win up to $100,000 in prizes! For a limited time, vendors submitting new applications to BlackBerry App World(TM) will have the opportunity to enter the BlackBerry Developer Challenge. See full prize details at: http://p.sf.net/sfu/Challenge _______________________________________________ Octave-dev mailing list Octave-dev@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/octave-dev
