Math Problem Statement

The matrix [A] has a norm of ||A||=3.2 x 103 and the norm of the inverse of that matrix is ||A-1||=2.5 x 1012. If a solution is obtained for a system of equations [A]x)={b} using this same matrix [A] and double precision computations, then 因 the solution is very sensitive to input error

the solution is insensitive to input error

small residuals indicate accurate answers

small residuals do not indicate accurate answers

the system is ill-conditioned

Solution

The given problem involves understanding the condition number of the matrix [A][A], which is a measure of how sensitive the solution to a system of linear equations is to input errors. The condition number κ(A)\kappa(A) is given by:

κ(A)=AA1\kappa(A) = ||A|| \cdot ||A^{-1}||

Substituting the given norms:

κ(A)=(3.2×103)(2.5×1012)=8.0×1015\kappa(A) = (3.2 \times 10^3) \cdot (2.5 \times 10^{12}) = 8.0 \times 10^{15}

This very large condition number (κ(A)=8.0×1015\kappa(A) = 8.0 \times 10^{15}) indicates that the matrix [A][A] is ill-conditioned. An ill-conditioned system is highly sensitive to input errors, meaning small changes in the input data can lead to large changes in the solution. This also implies that small residuals may not necessarily indicate accurate answers because the system's sensitivity can distort the solution even if the residuals appear small.

Therefore, the correct conclusion from the given options is:

  • the system is ill-conditioned
  • the solution is very sensitive to input error

If you have any questions or want further details, feel free to ask!

Here are 5 related questions for further exploration:

  1. What is the condition number, and how does it relate to matrix sensitivity?
  2. How does the condition number affect numerical stability in solving linear systems?
  3. What methods can be used to solve ill-conditioned systems of equations?
  4. How can the precision of computations impact the solution of ill-conditioned systems?
  5. What role do residuals play in evaluating the accuracy of a solution in an ill-conditioned system?

Tip: The larger the condition number, the more sensitive the system is to errors, which can cause significant instability in numerical solutions.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Condition Number
Numerical Stability

Formulas

κ(A) = ||A|| * ||A^(-1)||

Theorems

Condition Number and Sensitivity

Suitable Grade Level

Undergraduate Level