# [PD] matrix operations with audio signals

João Pais jmmmpais at gmail.com
Mon May 21 14:57:50 CEST 2018

```how about some dynamic patching using only simple objects such as *~,
sin~, etc.? although it will be hard to set it up with the necessary
matrix models, it could be more versatile in the long run (don't know how
many different operation combinations you'll need)

> OK that kind of answers my question: it would be easier to write the
> matrix equations out linearly since the use of the [mtx_*~] object is
> not immediately clear to me. Very much still learning this kind of math.
>
> Best!
> D.
>
> On 16/05/2018 19.46, IOhannes m zmölnig wrote:
>> 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

```