Questions tagged [tensor]
The tensor tag has no usage guidance.
21
questions
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21 views
Second fundamental form - Maple
I would like to know the command/line in Maple 16 or similar to obtain the second fundamental form tensor for a given metric. I've managed to obtain Rienmann and Ricci tensor, even Weyl, but I can't ...
4
votes
1answer
147 views
Is there a library that allows einstein summation on dense, sparse, and LinearOperator type tensors
Numpy's einsum only works with dense tensors.
Is there an alternative that also works with sparse tensors and linear operators?
For example, I might have a ...
1
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0answers
57 views
How to get the derivatives of the determinant and inverse of 2nd-order tensor wrt itself in SymPy?
I have a second-order tensor for which I need to compute the derivatives of its determinant and inverse w.r.t. itself. The equations are as follows:
$$\frac{\partial \, det(\mathbf{F})}{\partial F_{...
0
votes
1answer
70 views
Computing excited states using itensor (with DMRG)
I am trying to compute first few excited states of some Hamiltonian (I am using itensor and its DMRG algorithm). To do so, I am ...
0
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2answers
107 views
Second derivative in coordinate invariant form
To solve stationary, incompressible, inviscid and irrotational flow around a circular cylinder, I am using general coordinates. Since the flow is symmetrical, we only consider the upper half of the ...
1
vote
1answer
108 views
triple cross prouct of tensor
Im trying to compute a triple cross product of vectors a,b, and c in real space and integrate over the entire space. The result is a term in the hamiltonian for an electronic system so there are ...
1
vote
2answers
609 views
Derivative of the inverse of the Right Cauchy-Green Deformation Tensor wrt itself
In continuum mechanics, we define the Right-Cauchy-Green Deformation Tensor as
$\boldsymbol{C}=\boldsymbol{F}^T\boldsymbol{F}$
I want to compute $\frac{\partial \boldsymbol{C}^{-1}}{\partial \...
1
vote
0answers
91 views
Efficient out-of-place arbitrary rank GPU transpose
Summary: Is there an efficient out-of-place GPU tensor transpose operation that scales as $O(n)$ for tensors with $n$ total elements, regardless of the rank $d$? The naive algorithm costs $O(dn)$, ...
5
votes
3answers
1k views
Efficiently computing the product of a multi-dimensional matrix (or tensor) and vectors
Update: Thank you very much for all of you who answered below. I'm studying each answer now. In the long term, I'm more interested in solutions that work for sparse tensors (sorry I should have ...
1
vote
1answer
99 views
Binary tensor operations in Nutils [closed]
How does one write general tensor contractions in the Python-based finite element package Nutils? For example, how does one write the contraction of a fourth-order elasticity tensor $\boldsymbol{C}$ ...
9
votes
3answers
1k views
Second order tensor field visualization software
Is there an overview available over tensor visualization software?
My personal preference is:
A software which is free, well documented, and offers visualization techniques for different physical ...
0
votes
2answers
166 views
Vector and index notation equivalence
Given 2 vectors $\mathbf{u}$ and $\mathbf{v}$ the following are equivalent:
$\mathbf{u}\cdot\mathbf{v}$
$\mathbf{u}^T \mathbf{v}$
$u_i v_i$
$v_i u_i$
$\mathbf{v}\cdot\mathbf{u}$
$\mathbf{v}^T\...
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0answers
50 views
Optimization of nonlocal stencil-like operator on subset of regular grid
I am trying to optimize the execution time for this particular piece of fortran code.
Details:
i_gc is a (ngpts, 3) array of containing (i,j,k) indices for each grid point. This is a subset of the ...
0
votes
2answers
98 views
Explain this multivariate differential identity
$$ \frac{\partial|\nabla\phi|^2}{\partial\phi}=-2\nabla\cdot\nabla\phi$$
I would very appreciate that you help me . Please do it in detail, I am quite not good at such problems.
There is something ...
1
vote
0answers
152 views
What is the relation between Kruskal tensor and CP decomposition?
In Matlab Tensor Toolbox there is a tensor type called "Kruskal tensors", I found its form is similar to the CP decomposition.
Wikipedia mentioned:
"As such, many of the methods have been ...
1
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0answers
195 views
4th order tensor [closed]
I'm new with FEniCS and Python and I'm stuck with this issue:
is there a way to write a 4th order tensor in an easy way to implement?
I have to compute the following stiffnes tensor:
$A_{ijkl}= \...
1
vote
1answer
51 views
Anisotropic invariant expansion
I am trying to calculate the second and third invariants for a turbulent flow. I have the second order statistics (both transient and averaged). i.e $uu$, $vv$, $ww$, $uv$, $vw$ and $uw$. These are ...
1
vote
1answer
372 views
Any relation between the singular values of each flattening matrices and the core tensor out of Tucker decomposition?
Before I know how to do tucker decomposition, I mistakenly thought the core tensor is only from combining the singular value matrices of the flattening matrices. Yes I know it is not now.
For the ...
3
votes
1answer
215 views
Is there a reference/source paper for the TUCKER_ALS() in Tensor Toolbox for MATLAB?
TUCKER_ALS computes the best rank-(R1,R2,..,Rn) approximation of tensor X, according to the specified dimensions. I am using MATLAB Tensor Toolbox Version 2.5. I am wondering if I write a paper, how ...
2
votes
0answers
383 views
finite volume for diffusion equation with anisotropic (tensor) coefficient
Consider the scalar PDE for $u$ with Dirichlet boundary conditions:
$\mathrm{div}(\mathcal{K}\nabla u) = f\; \forall x\; \in \Omega \subset R^2$,
$u = 0 \; \forall \; x\;\in \partial\Omega$
...
20
votes
10answers
13k views
Fast, lightweight C++ tensor library for dimension-agnostic code
I am looking for a C++ tensor library that supports dimension-agnostic code. Specifically, I need to perform operations along each dimension (up to 3), e.g. calculating a weighted sum. The dimensions ...
