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Linear Algebra

Linear algebra is the detailed study of vector spaces. With applications in such disparate fields as sociology, economics, computer programming, chemistry, and physics, including its essential role in mathematically describing quantum mechanics and the theory of relativity, linear algebra has become one of the most essential mathematical disciplines for the modern world. Please direct all questions regarding matrices, determinants, eigenvalues, eigenvectors, and linear transformations into this category.

2,176 Questions

What are tensors?

A vector is a group of numbers in one dimensions; if you have such arrangements of numbers in more than one dimension, you get a tensor. Actually, a vector is simply a special case of a tensor (a 1st-order tensor).

What is the definition of a symmetric matrix?

Symmetric Matrix:

Given a square matrix A such that A'=A, where A' is the transpose of A, then A is a symmetric matrix.

note: No need to think about diagonal elements, they can be anything.

How do you graph this equation x plus 3y equal 6 please help?

x+3y=6

3y=6+x

y=2+x/3

So the best way is to plot the intercepts (easiest) which are:

if

x=0

therefore y=2 (0,2) is an intercept on the y-axis

y=0

0=2+x/3

-2=x/3

-6=x

so (-6,0) is the x-axis intercept

so plot those points and join a straight line through there. All you have to do is get two points since it is a straight line and will not turn and just draw a line through that.

How do you solve this math problem -25-x9?

The question contains an expression, not an equation nor inequality. An expression cannot have a solution.

What is a Boussinesq equation?

Check out http://en.wikipedia.org/wiki/Boussinesq_approximation.

Is 05 a solution to 5x-3y15?

If you are asking if x=0, y=5 is a solution to 5x-3y=15, then no. 0, -5 would be as if you sub in 0 for x you get 5(0) -3y=15, i.e. -3y=15, i.e. y=-5

How matrices used in engineering?

If you have a system, which can be expressed as a set of linear equations, then you can utilize matrices to help solve it. One example is an electrical circuit which uses linear devices (example are constant voltage sources and resistive loads). To find the current through each device, a set of linear equations is derived.

Is y equals -4x plus 3 linear?

Yes, y = -4x + 3 is a linear equation.

Is the moon orbit an example of a parabola?

No. Every closed orbit (around and around and around) is an ellipse.

Every open orbit (swish by one time and never return) is a hyperbola.

The one that's exactly precisely on the dividing line between closed and

open is a parabola.

What the difference between eigenvalue and eigenvector?

An eigenvalue is a scalar that indicates how much an eigenvector is stretched or compressed during a linear transformation represented by a matrix. In contrast, an eigenvector is a non-zero vector that remains in the same direction after the transformation, only scaled by the eigenvalue. Mathematically, for a square matrix (A), if (A\mathbf{v} = \lambda \mathbf{v}), then (\lambda) is the eigenvalue and (\mathbf{v}) is the corresponding eigenvector.

What are the singular values of an orthogonal matrix?

The singular values of an orthogonal matrix are all equal to 1. This is because an orthogonal matrix ( Q ) satisfies the property ( Q^T Q = I ), where ( I ) is the identity matrix. Consequently, the singular value decomposition of ( Q ) reveals that the singular values, which are the square roots of the eigenvalues of ( Q^T Q ), are all 1. Thus, for an orthogonal matrix, the singular values indicate that the matrix preserves lengths and angles in Euclidean space.

How do the graphs differ between equation and expression?

Graphs of equations typically represent a relationship between two variables, showing how one variable changes with respect to the other, often resulting in a curve or line. In contrast, expressions do not have an equality sign and do not define a relationship between variables; thus, they cannot be graphed as a function. Instead, expressions can represent values or calculations, which might be evaluated at specific points rather than graphed. Therefore, while equations can produce visual representations of relationships, expressions remain abstract without a graphical form.

Linear Systems and Functional Approximation Find the best least squares solution to the matrix equation AX equals b Where A equals 110 021 AND B equals 363?

To find the best least squares solution to the matrix equation ( AX = b ), where ( A = \begin{pmatrix} 1 & 0 \ 2 & 1 \end{pmatrix} ) and ( b = \begin{pmatrix} 3 \ 6 \end{pmatrix} ), we can use the formula ( X = (A^T A)^{-1} A^T b ). First, we compute ( A^T A = \begin{pmatrix} 1 & 2 \ 0 & 1 \end{pmatrix} \begin{pmatrix} 1 & 0 \ 2 & 1 \end{pmatrix} = \begin{pmatrix} 5 & 2 \ 2 & 1 \end{pmatrix} ). After finding ( (A^T A)^{-1} ) and multiplying by ( A^T b ), the least squares solution will yield the values of ( X ). The final values for ( X ) will be the best fit for the original equation.

Why does Phase 1 in linear programming have alternative optimal solutions?

Phase 1 of linear programming aims to find a feasible solution to the problem by minimizing a "penalty" function, often involving artificial variables. If the feasible region is unbounded or if multiple ways exist to achieve the same minimum value for the penalty function, there can be alternative optimal solutions. This occurs when the objective function is parallel to a constraint boundary, allowing for multiple feasible points that yield the same objective value. Hence, the presence of alternative optimal solutions is tied to the geometry of the feasible region and the nature of the objective function.

How can you recognize whether a real-world situation should be represented by an equation or an inequality?

To determine whether a real-world situation should be represented by an equation or an inequality, assess the nature of the relationship between the variables involved. If the relationship requires equality—where one quantity is exactly equal to another—you would use an equation. Conversely, if the situation involves a range of possible values, constraints, or conditions where one quantity is greater than, less than, or not equal to another, an inequality is more appropriate. For instance, budgeting scenarios often involve inequalities, while exact measurements may be represented with equations.

How do you inverse complex matrix with Armadillo linear algebra library?

To invert a complex matrix using the Armadillo linear algebra library, you can utilize the inv() function, which computes the inverse of a matrix. First, ensure you include the Armadillo header and link against the library. Here's a simple example:

#include <armadillo>

arma::cx_mat A = {{1.0, 2.0}, {3.0, 4.0}}; // Define a complex matrix
arma::cx_mat A_inv = inv(A); // Invert the matrix

Make sure the matrix is square and non-singular for the inversion to be valid.

What is a math dictionary?

A math dictionary (or a mathematics dictionary) is usually a dictionary of the definitions of common mathematical terms, formulae and examples of common diagrams and pictures for the uninitiated or those learning math.

How is a vector represented in a diagram?

It is usually represented by a lower case letter with a horizontal arrow above it. In print, the letter will usually be bold.

How to identify polynomial?

It is an expression with one variable, which is a linear combination of integral powers of that variable.

In simpler words, a polynomial in a variable x consists of a sum of a number of terms of the form axn where a is a number, called the coefficient and n is a positive integer.

What is physical interpretation of dot product?

it is physically the projection or shadow of a line on a plane...