[PD] Re: Some VASP questions

[Thomas Grill]

Oh, one more thing... with the fftscope-Patch there's a warning displayed
when you first bang the procedure.
This is because of a small bug in the new threading behavior of flext. I
fixed it - the version should be mirrored to the pd cvs in about half an
hour.

best greetings,
Thomas



----- Original Message ----- 
From: "Larry Troxler" <lt at westnet.com>
To: "Thomas Grill" <t.grill at gmx.net>; "PD List" <pd-list at iem.kug.ac.at>
Sent: Monday, November 10, 2003 3:22 AM
Subject: Re: Some VASP questions


> On Sunday 09 November 2003 20:36, Thomas Grill wrote:
> > You can either send a "detach 1" message before the first operation, or
> > even better, set the "detach" attribute at creation time by specifying
e.g.
> > [vasp.window @detach 1]. If you have newer vasp and pd versions, you
will
> > notice that the "@detach 1" disappears, but you can use the properties
> > dialog in the context menu (right mouse click) to display the attributes
of
> > vasps objects (or rather all attribute-enabled flext objects)
> >
>
> <various stuff snipped for your concise viewing pleasure>
>
> > detach
>
> Ok, I didn't know you could do that at creation time - that's what I want.
>
> > > Next, "vasp.window" apparently doesn't handle the "to" message
>
> > vasp.window fills a buffer with a window curve, so a separate
destination
> > won't make much sense.
> > There's vasp.*window to multiply half of a window with some data, or
> > vasp.*xwindow for a symmetric version (these two have a @to attribute)
> >
>
> Yes, I misunderstood - I thought that that vasp.window already multiplied
the
> existing buffer with its window.
>
> > > Now about the fft stuff - I am not sure what vasp.rfft does actually.
It
> > the vasp.rfft operation produces the following output
> > bin 0 .... frequency 0 component
> > bin 1... windowsize/2-1 ... real part of the spectrum (only positive
> > frequencies)
> > bin windowsize/2 ... Nyquist freqency component
> > bin windowsize/2+1... windowsize-1 ... complex part of the spectrum
(only
> > positive frequencies)
> >
> > There's no redundancy of data as expected for a real FFT.
> > A magnitude operation has to be performed separately afterwards.
> >
> > > IOW basically, for an FFT of a real signal, I only want the first
half,
> > See the attached patch... it probably does what you want to do....
> >
> > best greetings,
> > Thomas
>
> Taking a look in 3.. 2.. 1..
>
> Larry
>
>