[PD] get sinusoid from a sine and a cosine oscillator

Alexandros Drymonitis adrcki at gmail.com
Wed Jan 29 21:44:57 CET 2014

Yeah, well I'm trying to create shapes in Gem (say a circle) and create the
sound they make. So, to make a circle, I'm making a ramp from 0 to 1,
multiply it by 2pi and send it to [cos] and [sin] and store these values in
two tables, which I then read for every instance of a [circle] (using
[repeat] and [separator]). So, since for any shape, you need two
coordinates, x and y, my thought was to use these two coordinates as the
real and imaginary part of an FFT, merging the two dimensions in one.
After the sinusoid, I'll try to make other shapes too, but I wanted to
start from that to make sure that I hear exactly what I see.

On Wed, Jan 29, 2014 at 10:30 PM, Charles Z Henry <czhenry at gmail.com> wrote:

> What you seem to be doing is creating a spectrum which has magnitude 1
> everywhere, and the phase is varying at a constant rate vs frequency.  That
> means it has a constant group delay.
>
> So... my guess is that you'd get an impulse in each block, whose timing
> depends on the rate of the phasor.  When you vary the phasor frequency, it
> will coincide with the peak of the hann window at some point and be its
> loudest.
>
> Should be a periodic complex tone.  I don't understand your goal:  you've
> got sinusoids in the patch... to generate sinusoids?
>
> Chuck
>
>
> On Wed, Jan 29, 2014 at 9:12 AM, Alexandros Drymonitis <adrcki at gmail.com>wrote:
>
>> Say I have a full sine and a full cosine cycle stored in two tables. I'm
>> trying the following to get a sinusoid from [rifft~] but it doesn't work.
>>
>> [phasor~]
>> |
>> [*~ sizeOfTable - 3]
>> |
>> [+~ 1]
>> |\
>> | \
>> |  [tabread4~ sine]
>> |   \
>> |      \
>> [rifft~]
>> |
>> |    [tabreceive~ hann]
>> |    |
>> [*~ ]
>> |
>> [/~ 1536]
>>
>> I've set the block size to 1024 in this subpatch, and there's a hann
>> window in the parent patch as well. The tables have three guard points,
>> that's why I'm multiplying [phasor~] by the size of the table minus three
>> and then add one.
>> The output of this is a waveform with very low amplitude that kind of
>> bounces up and down within a sine like mask. Don't know if I'm making my
>> self clear. My main question is, how do you get a sinusoid out of a sine
>> and a cosine? Also, what's wrong in my approach?
>>
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