Matrix Function - Check Understanding

In summary, the matrix ##\begin {pmatrix} 0&1\\-1&0\\ \end {pmatrix} ## rotates a vector by ##\pi/2## clockwise, as seen by multiplying a general point (x,y) in the ##R^2## plane by the matrix and observing where it ends up. This can also be confirmed by looking at the rotation matrix formula and finding that it satisfies the values of ##\cos \theta = 0## and ##\sin \theta = -1##.
  • #1
Poetria
267
42
Homework Statement
I have computed the matrix (it's ok):

##\begin{pmatrix}
0&1\\
-1&0\\
\end{pmatrix}##

The question is: what does this matrix do?
Relevant Equations
To figure it out, I have sketched two vectors:
[2,3] and the other - after transformation: [3,-2]
I would say that what this matrix does is rotate e.g. a vector by ##\pi/2## clockwise. Am I right?
I would like to check my understanding.
 
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  • #2
First, you have a mistake in the result for [2,3]. You need to correct that. Then take a general point, (x,y), in the ##R^2## plane and multiply it by the matrix. That will tell you where it ends up.
 
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  • #3
FactChecker said:
First, you have a mistake in the result for [2,3]. You need to correct that. Then take a general point, (x,y), in the ##R^2## plane and multiply it by the matrix. That will tell you where it ends up.
Right, I have corrected it. :(
 
  • #4
Poetria said:
Right, I have corrected it. :(
I agree with your statements.
 
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  • #5
##\begin {pmatrix} 0&1\\-1&0\\ \end {pmatrix} \times \begin {pmatrix} x\\ y\\ \end{pmatrix} = \begin {pmatrix} y\\ -x\\ \end {pmatrix}##
 
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  • #6
Great. :) Thank you so much. :)
 
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  • #7
Poetria said:
Homework Statement:: I have computed the matrix (it's ok):

##\begin{pmatrix}
0&1\\
-1&0\\
\end{pmatrix}##

The question is: what does this matrix do?
Relevant Equations:: To figure it out, I have sketched two vectors:
[2,3] and the other - after transformation: [3,-2]

I would say that what this matrix does is rotate e.g. a vector by ##\pi/2## clockwise. Am I right?
I would like to check my understanding.
You can look up the rotation matrix here:

https://en.wikipedia.org/wiki/Rotation_matrix

In your case, you are looking for ##\cos \theta = 0## and ##\sin \theta = -1##. This is satisfied by ##\theta = -\frac \pi 2##
 
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  • #8
Many thanks. :)
PeroK said:
You can look up the rotation matrix here:

https://en.wikipedia.org/wiki/Rotation_matrix

In your case, you are looking for ##\cos \theta = 0## and ##\sin \theta = -1##. This is satisfied by ##\theta = -\frac \pi 2##
 
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1. What is a matrix function?

A matrix function is a mathematical function that takes a matrix as its input and produces another matrix as its output. It can be thought of as a function that operates on matrices, similar to how regular functions operate on numbers.

2. How is a matrix function different from a regular function?

A matrix function differs from a regular function in that it operates on matrices instead of individual numbers. This means that the input and output of a matrix function are both matrices, whereas a regular function takes in a single number and produces a single number as its output.

3. What are some common examples of matrix functions?

Some common examples of matrix functions include matrix addition, matrix multiplication, and matrix inversion. Other examples include functions like trace, determinant, and eigenvalues, which take in a matrix as their input and produce a single number as their output.

4. How is the understanding of matrix functions important in scientific research?

Matrix functions are essential in scientific research because they allow for the manipulation and analysis of data that is organized in a matrix format. Many scientific fields, such as physics, economics, and engineering, use matrix functions to model and solve complex problems.

5. What are some tips for understanding matrix functions?

Some tips for understanding matrix functions include familiarizing yourself with basic matrix operations, such as addition, multiplication, and inversion, as well as understanding the properties and rules that govern these operations. It is also helpful to practice using matrix functions in real-world applications to gain a better understanding of how they work.

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