What is the square of a column vector?

In summary, there is a matrix property that can be applied to take the square of a column vector, which is represented by {\bf x}{\bf x}^T or {\bf x}^T{\bf x}. The size of the resulting matrix depends on the operation used, with {\bf x}{\bf x}^T resulting in a 3x3 matrix and {\bf x}^T{\bf x} resulting in a 1x1 matrix. However, it should be noted that the square of a vector typically refers to the scalar product, which can be represented as (xT)x.
  • #1
devonho
8
0

Homework Statement



Hi,

Is there a matrix property that can be applied to take the square of a column vector?

Something like:

[itex]{\bf x}=\left[x_1,x_2,x_3\right]^T[/itex]
[itex]\left[{\bf x}\right]^2[/itex]
[itex]={\bf x}{\bf x}^T[/itex]
or
[itex]={\bf x}^T{\bf x}[/itex]?

Thank you.


Homework Equations





The Attempt at a Solution

 
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  • #2
devonho said:

Homework Statement



Hi,

Is there a matrix property that can be applied to take the square of a column vector?

Something like:

[itex]{\bf x}=\left[x_1,x_2,x_3\right]^T[/itex]
[itex]\left[{\bf x}\right]^2[/itex]
[itex]={\bf x}{\bf x}^T[/itex]
or
[itex]={\bf x}^T{\bf x}[/itex]?

Thank you.
...
What is the size of the matrix: [itex]={\bf x}{\bf x}^T\,?[/itex]

What is the size of the matrix: [itex]={\bf x}^T{\bf x}\,?[/itex]
 
  • #3
Hi SammyS,

[itex]{\bf x}{\bf x}^T[/itex] is 3x3
while
[itex]{\bf x}^T{\bf x}[/itex] is 1x1
 
  • #4
I'm not sure what you mean by the square of a column vector...
 
  • #5
Generally the square of a vector refers to the scalar product, which you can crudely think of as a 1 by 1 matrix. Therefore, the answer is (xT)x .
 

1. What is a column vector?

A column vector is a type of mathematical notation used to represent a list of numbers or variables arranged in a vertical column. It is often used in linear algebra and is denoted by a bold lowercase letter with a single column of numbers or variables beneath it.

2. How is a column vector different from a row vector?

A column vector is different from a row vector in terms of its orientation. A column vector has a single column of numbers or variables, while a row vector has a single row. In other words, a column vector is written vertically, while a row vector is written horizontally.

3. What does it mean to square a column vector?

Squaring a column vector means multiplying each element in the vector by itself. This can also be thought of as finding the dot product of the vector with itself. The result of squaring a column vector is another column vector with the same number of elements, where each element is squared.

4. How is the square of a column vector represented mathematically?

The square of a column vector is represented by raising the vector to the power of 2, denoted by a superscript 2. For example, if we have a column vector v, its square would be represented as v2. This indicates that each element in the original vector has been squared.

5. What is the purpose of squaring a column vector?

Squaring a column vector is often used in mathematical calculations and equations, particularly in linear algebra and vector calculus. It can also be used to represent certain physical quantities, such as velocity or acceleration, that have both magnitude and direction.

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