The Orthogonality of Vectors and Matrices

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Discussion Overview

The discussion revolves around the concept of orthogonality in vectors and matrices, specifically addressing the relationship between orthogonal vectors and orthogonal matrices. Participants explore the definitions and implications of orthogonality in the context of linear algebra.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether three orthogonal vectors imply that the corresponding matrix is orthogonal and whether the inverse of that matrix is its transpose.
  • Another participant clarifies that a matrix is orthogonal if its columns are orthonormal.
  • A participant seeks to understand how to check if the columns are orthonormal, suggesting that orthonormality requires the dot product of distinct vectors to equal zero.
  • A later reply provides a criterion for orthonormality using the Kronecker delta, indicating that the dot product of vectors should yield 1 when they are the same and 0 otherwise.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the implications of orthogonal vectors for matrices, and there are competing views regarding the definitions and checks for orthonormality.

Contextual Notes

Some assumptions about the definitions of orthogonality and orthonormality may not be explicitly stated, and the discussion does not resolve the mathematical steps necessary to fully understand the implications of these concepts.

Petrus
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Hello MHB,
I wounder if I did understand correct, If we got 3 vector and they all are orthogonala, $$v_1=(x_1,y_1,z_1)$$,$$v_2=(x_2,y_2,z_2)$$,$$v_3=(x_3,y_3,z_3)$$ does that also mean that the matrix orthogonal so the invrese for the matrix is transport?

Regards,
$$|\pi\rangle$$
 
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Close, but not quite. A matrix being orthogonal means that its columns are orthonormal.
 
Ackbach said:
Close, but not quite. A matrix being orthogonal means that its columns are orthonormal.
How can I check if a columns are orthonormal? If I got it correct if $$v_1,v_2,v_3$$ shall be orthonormal that means that $$v_1*v_2*v_3=0$$

Regards,
$$|\pi\rangle$$
 
Check that $v_{i} \cdot v_{j}=\delta_{ij}$. Here
$$\delta_{ij}=\begin{cases}0,\quad &i \not=j \\ 1,\quad &i=j \end{cases}$$
is the Kronecker delta.
 

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