Hi - mea culpa - as pointed out by a colleague (and documented in the help
document for "hanning" in Matlab), this function produces the same window,
but without the first and last zero-weighted samples.
Cheers -- Ariel
On Tue, Feb 9, 2010 at 4:58 PM, Ariel Rokem <arokem@...> wrote:
> Hi everyone,
> Mystery solved (I think)! It turns out that matlab has two functions, one
> called "hann" and the other called "hanning". They both purport to produce
> the hanning window, but they produce two (slightly) different things. Only
> one of these (the one given by "hann") actually produces the hanning window
> as it is defined in the standard reference on this (Harris 1978. And also
> Wikipedia ;D). When using the "hann" function in Matlab in this little
> experiment, the difference between the python and the matlab results, is on
> the order of %10e-6. I think I am willing to live with that.
> The only mystery that remains (I think) is - what is Matlab's "hanning"
> supposed to be doing? Are there two different windows: hann and hanning (not
> "hamming" - I know that's a different one)?
> On Mon, Feb 8, 2010 at 9:32 AM, Ariel Rokem <arokem@...> wrote:
>> Hi -
>> the maximal difference in this case is of about 6 (units?), which is an
>> approximately 50% difference. This is in one point in the spectrum which has
>> a relatively small value - the maximal peaks in the spectra are on the order
>> of 1200, so in the grand scheme of things, not that horrible. Other large
>> differences are on the order of 4, which is approximately 5% or less of
>> those points.
>> Thanks - Ariel
>> PS for some reason, matplotlib-devel will not get your email unless you
>> hit "reply all", so they have been getting my emails, but not yours. I am
>> not sure whether that is what you intended, so I thought I would mention it.
>> On Mon, Feb 8, 2010 at 1:24 AM, Ludwig Schwardt <
>> ludwig.schwardt@...> wrote:
>>> On Mon, Feb 8, 2010 at 5:25 AM, Ariel Rokem <arokem@...> wrote:
>>> > I don't think that the cause of the discrepancy is because of the
>>> > hamming/hanning window difference. I do set the window in the matlab
>>> part to
>>> > also be a hanning window of length nfft.
>>> I suspected you gave the same window to both, but I was just
>>> checking... :-) To find those smaller discrepancies might be a bit
>>> harder then, requiring a careful comparison of the various steps
>>> involved. Just for interest's sake, how big are the differences we are
>>> talking about?
>> Ariel Rokem
>> Helen Wills Neuroscience Institute
>> University of California, Berkeley
> Ariel Rokem
> Helen Wills Neuroscience Institute
> University of California, Berkeley
Helen Wills Neuroscience Institute
University of California, Berkeley