# Tag Info

Accepted

### Nearest Kronecker Product

The Pitsianis-Van Loan algorithm turns out to be surprisingly easy to implement in Mathematica: ...
Accepted

### Python's einsum equivalent in Mathematica?

You can implement most of your einsum functionality using TensorContract/TensorTranspose. ...
• 123k
Accepted

• 8,373

### SymmetrizedArray of stiffness/compliance tensor

This is very late to the party, but someone might still be interested. You can do what you want by solving the conditions of the material symmetry group. My answer is organized in 1) Background ...
• 5,283
Accepted

### Dot Product of Block Matrices

One way is to turn them into ordinary matrices, take the dot product, and then ArrayReshape them into the form you want. ...
• 5,354

### Summation of Kronecker deltas should give the dimension

You could just do: Sum[KroneckerDelta[μ, ν] KroneckerDelta[μ, ν], {ν, d}, {μ, d}, Assumptions->d>1] d Although it might make sense to use symbolic ...
• 123k

### How to implement Einstein summation convention with differential operators

Let me try to partially answer. Partially for the following reason: I know how to implement index vector and tensor notations and how to work with them. I also wanted to implement the Einstein ...
• 34.8k

### Array reshaping without explicitly specifying one dimension

ArrayReshape doesn't let you do this, but ReshapeLayer does: ...
• 17.9k

### Symbolic tensor simplifications and the identity matrix

I agree that it's a bit odd that Mathematica doesn't simplify these expressions with its built-in functions, especially in the symbolic tensor language (i.e. using ...
• 5,921
Accepted

### How to define an orthogonal basis in the right way?

You can combine the best of both worlds: symbolic tensors and vectors on one hand, and explicit vectors on the other. Explicit vectors are necessary in most vector algebra operations, unless you want ...
• 95k

### Compute a double dot product between two tensors of rank 3 and 2

The double dot product is also known as the Frobenius inner product--in other words, it is the result of flattening the matrices and treating them as vectors. So, here is another way to write it: <...
• 22.5k
Accepted

### How to create simple (tensor) product spaces?

Here is the basic method, illustrated with the combination of two spin-1/2 particles. (Hopefully, the physics language is familiar or accessible; I don't really have an idea of where else this kind of ...
• 21.5k