[PD] matrix operations with audio signals

IOhannes m zmölnig zmoelnig at iem.at
Wed May 16 18:46:43 CEST 2018


On 05/16/2018 04:56 PM, Derek Holzer wrote:
> On deeper inspection: [mtx_pack~] gives the same value to an entire row,

how so?
if i feed an [osc~ 440] into the first inlet of [mtx_pack~ 3] the first
row will contain 64 samples of a sine wave.

> 
> If [matrix~] is used to process the vectors which represent a cube,
> let's say, and I want the cos, sin, and -sin of the rotation angle R to
> be audio signals, how could I use [matrix~] to do that?
> 

first: [matrix~] is deprecated. you should use [mtx_*~] instead. (you
should get a big fat red warning for each and every [matrix~] object you
create; if you don't, you are using a version of iemmatrix that is more
than 15 years old).

anyhow, what you want to do can be done without [mtx_*~], doing the
matrix multiplication on paper and then building the patch discretely.

for simplicity here's a 2D version using [expr~]:

                       R
                       |
X            Y         [expr~ cos($v1);sin($v1)]
|            |         |              |
[expr $v1*$v3+$v2*$v4; $v2*$v3-$v1*$v4]
|                                     |

gfmasrd
IOhannes

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