Skip to main content

# Questions tagged [matrix]

For questions about using and representing matrices on a computer in order to solve computational problems. Should generally also include a tag about the specific property/problem you are solving (e.g. [tag:linear-algebra], [tag:eigenvalues], [tag:inverse].

613 questions
Filter by
Sorted by
Tagged with
0 votes
0 answers
31 views

### Lumped (diagonal) vs. consistent (non-diagonal, symmetric) mass matrix in Nastran

I've been tinkering with DMAP to explore the procedure followed by Nastran when solving a complex modes analysis. I've reached a passage I cannot understand: at some point Nastran formulated what it ...
0 votes
1 answer
73 views

### What do diagonal (DOF-to-self) terms of stiffness matrix physically mean?

I am used to interpreting each entry of a solid mechanic system's stiffness matrix as a 1D (linear or angular) spring joining one DOF (column index) to another (row index). But this interpretation ...
4 votes
1 answer
111 views

### Optimized Lanczos method for finding eigenvalues of $A \otimes B$

Recently my supervisor told me about an efficient way to calculate eigenvalues and eigenvectors of matrix $A \otimes B$ with $a_{1} \times a_{2}$ as dimensions of $A$ and $b_{1} \times b_{2}$ is of $B$...
1 vote
0 answers
57 views

### Orthogonal Transformation of Hessenberg Matrices

$H\in\mathbb{R}^{n\times n}$ is an upper Hessenberg matrix. Suppose $\lambda$ is an eigenvalue of $H$ and $x$ is an eigenvector w.r.t. $\lambda$. Is there any fast algorithm that can find an ...
• 111
2 votes
2 answers
170 views

• 436
5 votes
0 answers
45 views

### Lowest eigenvalues of a matrix with divergent entries

In high energy physics we oftentimes encounter the following problem. For a given parametrized matrix $\{H_{ij}(\Lambda)\}$, we know that in the limit $\Lambda\to\infty$ some of its entries become ...
• 151
3 votes
1 answer
192 views

### Using submatrices of matrix decomposition for solving a large number least-squares problems

I want to decrease the computational time for solving a large number (>1000) of least-squares problems. Given a matrix, the system matrix for each least-squares problem is a submatrix of the given ...
• 219
1 vote
1 answer
246 views

• 41