# [PD] matrix operations with audio signals

Derek Holzer macumbista at gmail.com
Wed May 16 18:52:23 CEST 2018

```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
>
>
>
> _______________________________________________
> Pd-list at lists.iem.at mailing list
> UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
>

--
derek holzer
noise.art.technology
http://macumbista.net

```