Are you able to solve this Simple Matrix Challenge?

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Discussion Overview

The discussion revolves around solving a problem involving 2 by 2 matrices, specifically focusing on the equations L = PTP and X = PTTTTTTP, where L and X are known matrices and P and T are unknowns. The scope includes mathematical reasoning and exploration of potential solutions.

Discussion Character

  • Exploratory
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant presents the equations L = PTP and X = PTTTTTTP, seeking solutions for the unknown matrices P and T.
  • Another participant suggests testing a simple special case with specific values for L and X to explore the problem further.
  • A different participant provides numerical examples of matrices P and T, illustrating the challenge of retrieving P and T from known L and X.
  • Concerns are raised about the potential for ambiguous solutions, particularly if P is not constrained to specific values.
  • One participant notes that if the equation were L = PTP-1, the problem would be simpler, indicating a perceived increase in complexity with the current formulation.
  • Another participant questions the simplicity of the problem, suggesting that changes in matrix elements (e.g., to complex or differential variables) could complicate the situation further.
  • A final participant asserts that the problem is underdefined, highlighting that substituting P with -P would yield the same equations, indicating a lack of uniqueness in the solution.

Areas of Agreement / Disagreement

Participants express differing views on the complexity and solvability of the problem, with some suggesting it is simple under certain conditions, while others argue that it is inherently ambiguous and underdefined. No consensus is reached regarding the nature of the problem.

Contextual Notes

The discussion highlights limitations related to the assumptions about the matrices, such as their invertibility and the implications of different values for P. The potential for multiple solutions and the impact of matrix element types are also noted but remain unresolved.

blurking132
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I am working with 2 by 2 matrices, L, X, P and T.

L = PTP -------Eqn 1
X = PTTTTTTP ----------Eqn 2

where L and X are known matrices. P and T matrix are unknown and are to be solved.

The above problem looks simple but are you able to solve it?
 
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Can you do a simple special case? for example

[tex] L = \left[1, 0; 0, 1\right], X = \left[0, 1; 0, 0\right][/tex]
 
Let's use some numbers as an illustration.
For example,
P = [1 1;1 1]; T = [ 1 2;3 4 ];
L = P*T*P = [10 10;10 10];
X = P*T*T*T*T*T*T*P = [44966 44966;44966 44966];

We only have L and X. The problem is how to get back P and T.
 
it seems to be solving some linearlity problem,
however this question can lead to ambiguos solutions,
i assume your question is bound to only by setting the P to be [1,1;1,1],
otherwise this question is meaningless.

i don't know, perhaps I'm wrong? why don't you propose your solution since you're confident and done some research?
 
If it were L= PTP-1, the problem would be simple. But with L= PTP, ...
 
and i doubted that if the elements within changed,
would it still be "simple" ?

for e.g, complex element, exponential, differential variable?


And it definitely not 'simple' as it looks,
from the first view it is already harzardous.
 
I am sorry to tell you that your problem is under defined. Even if we assume all matrices to be invertible you will get the same equations if you substitute P for -P.
 

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