LInear algebra coding question

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SUMMARY

The discussion focuses on creating a coding matrix A such that its inverse A-1 contains no fractions. The consensus is that multiplying several type III matrices together ensures that the determinant of A equals 1, which is essential for the inverse to remain integer-based. An upper triangular matrix is also suggested, as its determinant is inherently 1, simplifying the process of achieving the desired properties. The conversation touches on the specific case of 2x2 matrices, where the condition ad-bc = 1 guarantees the absence of fractions in the inverse.

PREREQUISITES
  • Understanding of matrix operations, particularly determinants
  • Familiarity with type III matrices
  • Knowledge of upper triangular matrices
  • Basic concepts of linear algebra and matrix inverses
NEXT STEPS
  • Research the properties of type III matrices in linear algebra
  • Learn about determinants and their role in matrix inverses
  • Explore the construction of upper triangular matrices
  • Investigate the general case for nxn matrices and conditions for integer inverses
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Students studying linear algebra, particularly those tackling matrix theory and coding matrices, as well as educators looking for effective teaching strategies in matrix operations.

Mdhiggenz
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Homework Statement


Describe how to create a coding matrix A so that A-1
has no fractions

The answer is Multiply a few type III matrices together, so that det A = 1

What I put is to just use an upper triangular matrix, since the det of an upper triangular matrix is 1 and you have to do row operations in order to get the matrix into an upper triangular form.

Not sure if answer would be accepted as partially correct.

Homework Equations





The Attempt at a Solution

 
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Presuming you're working your matrix over the integers, it's easy to create an encrypting matrix so that its decoding matrix will have no fractions in it.

You're correct for the case of 2x2 matrices, as long as ad-bc = 1, you're good to go. I'm not sure for the general nxn case though.
 

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