determing matrices

[David Stahl]

Hi!


I like to solve the following problem:

I got 4 known input vectors (1x4) : X_1..4 and 4 known output vectors
(1x4) : Y_1..4.

M x X_1...4 = Y_1...4

So, there is a transformation matrix 4x4 which describes the transformation
of the 4 input vectors to the output vectors.
My problem is to determine this matrix . Labview offers only a vi which
determines a unknown Input vector X for a known Matrix M and a known output
vector Y.
Does anybody know a way to determine the Matrix with this vi? Or is there
any other VI which fits to this problem?
I can't imagine there is no one who didn't have this problem before.....


Thanx,


David

[Jean-Pierre Drolet]

Hello

it is quite staightforward:

Make 2 matrices X and Y with your vectors as column of the matrix

you have the equation

M*X = Y

thus M = Y*(X^(-1))



David Stahl a écrit dans le message :
81gumc$190$1@news.BelWue.DE...
> Hi!
>
>
> I like to solve the following problem:
>
> I got 4 known input vectors (1x4) : X_1..4 and 4 known output
vectors
> (1x4) : Y_1..4.
>
> M x X_1...4 = Y_1...4
>
> So, there is a transformation matrix 4x4 which describes the
transformation
> of the 4 input vectors to the output vectors.
> My problem is to determine this matrix . Labview offers only a vi which
> determines a unknown Input vector X for a known Matrix M and a known
output
> vector Y.
> Does anybody know a way to determine the Ma
trix with this vi? Or is there
> any other VI which fits to this problem?
> I can't imagine there is no one who didn't have this problem before.....
>
>
> Thanx,
>
>
> David
>
>

[Walter Petermann]

David Stahl wrote:
>
> Hi!
>
> I like to solve the following problem:
>
> I got 4 known input vectors (1x4) : X_1..4 and 4 known output vectors
> (1x4) : Y_1..4.
>
> M x X_1...4 = Y_1...4
>
> So, there is a transformation matrix 4x4 which describes the transformation
> of the 4 input vectors to the output vectors.
> My problem is to determine this matrix . Labview offers only a vi which
> determines a unknown Input vector X for a known Matrix M and a known output
> vector Y.
> Does anybody know a way to determine the Matrix with this vi? Or is there
> any other VI which fits to this problem?
> I can't imagine there is no one who didn't have this problem before.....
>
> Thanx,
>
> David

David,
this looks like 4 equations and 16 unknowns. You
could try a web
search on 'pseudo inverse' (for x), then figure out the vi's you
need to implement the algorithm. The Labview advanced analysis
package might have a vi already made.

Walter

[labview user]

David Stahl wrote in message <81gumc$190$1@news.BelWue.DE>...
>Hi!
>
>
>I like to solve the following problem:
>
>I got 4 known input vectors (1x4) : X_1..4 and 4 known output vectors
>(1x4) : Y_1..4.
>
>M x X_1...4 = Y_1...4
>
>So, there is a transformation matrix 4x4 which describes the transformation
>

Send more details and I am sure we can put this to sleep for you.