How can I solve for a vector in a tensor equation involving dot products?

In summary, the conversation discusses the issue of solving for a vector using an equation involving tensors. It is mentioned that in order to find a solution, more constraints need to be imposed on the vector. A simple example in two dimensions is given to illustrate this concept.
  • #1
zephyr5050
21
0

Homework Statement



I'm currently trying to work through some issues I'm having with tensor and vector analysis. I have an equation of the form
$$\textbf{a} \bullet \textbf{b} = \textbf{c} \bullet \textbf{d}$$
where all quantities here are vectors. I want to solve for ##\textbf{b}## by finding an equation of the form
$$\textbf{b} = \overline{\textbf{T}} \bullet \textbf{d}$$
where ##\overline{\textbf{T}}## is a tensor. However I'm not sure the proper mathematical procedure to go about this. Any suggestions?

Homework Equations



That's what I'm here for.

The Attempt at a Solution



No idea.
 
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  • #2
Hi. You can't possibly do that without imposing more constraints on your vector:
In tensor language, the vectors are contracted on both sides so you can't "solve" for b.
This may be confusing because a⋅b looks like a vector expression but it's really a scalar; if you want to solve for a vector you need a vector expression.
Look at the simplest example in 2 dimensions:
a⋅b = cd ⇔a1b1 + a2b2 = c1d1 + c2d2
You see that you would need two equations to solve for the two variables b1 and b2 , and for every additional dimension you need an additional constraint...
 

FAQ: How can I solve for a vector in a tensor equation involving dot products?

What are vectors and tensors?

Vectors and tensors are mathematical objects used to represent physical quantities such as forces, velocities, and stresses. Vectors are quantities that have both magnitude and direction, while tensors are quantities that have magnitude, direction, and multiple components in different directions.

What are some common operations performed on vectors and tensors?

Some common operations performed on vectors and tensors include addition, subtraction, multiplication by a scalar, dot product, cross product, and tensor contraction. These operations are used to manipulate and analyze the properties of vectors and tensors.

How are vectors and tensors used in physics and engineering?

Vectors and tensors are used in physics and engineering to describe and solve problems involving motion, forces, stresses, and other physical quantities. They are also used in fields such as computer graphics, computer vision, and machine learning.

What is the difference between a vector and a tensor?

The main difference between a vector and a tensor is the number of components they have. Vectors have only magnitude and direction, while tensors have magnitude, direction, and multiple components in different directions. Additionally, vectors can be represented as a single column or row of numbers, while tensors require multiple rows and columns to represent their components.

How can one practice and improve their understanding of vectors and tensors?

One can practice and improve their understanding of vectors and tensors by solving exercises and problems that involve these mathematical objects. This can include geometric interpretations, algebraic manipulations, and applications in physics and engineering. Additionally, studying and reviewing the properties and operations of vectors and tensors can also help improve understanding.

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