Mathlab and least square problem

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Discussion Overview

The discussion revolves around the accuracy of MATLAB in calculating least squares solutions, particularly in the context of a specific overdetermined system represented by matrices A and b. Participants explore the implications of MATLAB's methods for solving such problems.

Discussion Character

  • Technical explanation, Debate/contested, Homework-related

Main Points Raised

  • One participant inquires about the accuracy of MATLAB's least squares solution without providing specific context.
  • Another participant asks for clarification on the specific problem being addressed.
  • A participant presents a specific 4x4 matrix A and a corresponding 4x1 vector b, along with their calculated residuals and null space, questioning MATLAB's accuracy in this case.
  • Another participant seeks to clarify whether the original question pertains to how MATLAB selects a solution for an overdetermined system.

Areas of Agreement / Disagreement

The discussion does not reach a consensus, as participants are exploring different aspects of the question and seeking clarification rather than agreeing on a specific answer.

Contextual Notes

Participants have not provided details on the assumptions underlying their calculations or the definitions of accuracy they are using, which may affect the interpretation of MATLAB's performance.

hytuoc
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Does anyone know how accurate is MATLAB in calculating least square solution?
Thanks!
 
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A=[1,1,1;-1,3,1;2,3,-2;1,3,2] A is 4X4

b=[4;0;1;2] ; b is 4X1

I calculated x^ (residual of x) to be [1.4127; -.0159; .8889]
r(x^) = b-A*x^ = [1.7143; 0.5714; 0; -1.1429]
Nul(A')=[-1.5;-.5;0;1]
so how accurate is MATLAB in calculating least square solution?
 
anyone know the answer to my question above?
 
Are you asking how does Matlab choose the solution when you give it an overdetermined system?
 

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