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On 2013-07-09 03:14, João Pais wrote:

Hello,

I'm programming a gui for [mtx_mul~], and it's almost finished. One

the one and only proper way to do signal matrix multiplication with "iemmatrix" is to use [mtx_*~] (rather than [mtx_mul~], [mtx_mul_line~] or [matrix~]).

thing is missing, and I wanted to know if someone already has a solution for it, before I break my head trying to find one.

I need to find a way to "rotate" matrixes, in order to coordenate the controler display, and matrix's format. Following the logic of max's matrixctrl object, and an usual DAW's display of audio matrixes, the lines are the inputs, and the columns are the outputs. But, Pd's [matrix] practise is the opposite.

the original matrix-multiplication object had this notation, but it was deprecated because you will find virtually no literature that does it like this.

[mtx_*~] follows the notation you will find in pretty much any scientific publication, that deals with matrix multiplication of signals: y = A * x with x = input signals, A = matrix, y = output signals.

if you want to matrix 4 inputs into 2 outputs, your matrix must look like: [2,N] = [2,4] * [4,N] out = A * in see http://en.wikipedia.org/wiki/Matrix_multiplication (for the sake of simplicity N would be one, though in practice it's the blocksize=64; anyhow, we can pretty much ignore it).

as you can see, this is a matrix with 2 lines and 4 columns.

(the original matrix multiplication object had reversed the multiplication (y = x * A) which nicely gave you A=[4,2], but was so uncommon a notation, that i found all of my collegues constantly looking up the help-patches when their code would not work - esp. when using square matrices)

whether this matches the DAW experience or not, is something else. in order to transform an [m,n] matrix into an [n,m] matrix, you can simply apply a "transpose" operation. see http://en.wikipedia.org/wiki/Transpose

be careful with your wording in matrix world: pretty much everything is standardized and traditional (like the "proper" way to multiply a bunch of signals by a matrix - the reason why [mtx_*~] behaves as it does). "matrix rotation" usually means something along the lines of mulitplying a coordinate set with a special matrix in order to achieve a spatial rotation of the coordinates: http://en.wikipedia.org/wiki/Matrix_rotation

fgamsdr IOhannes