Summary

1. Enable tranpose for first-order tensor
2. Add pseudo-inverse for Vec{dim}, Tensor{2,dim}, SymmetricTensor{2, dim}, Tensor{4, dim}, SymmetricTensor{4, dim, T}.

• In the Vec{dim} case, pinv produces Transpose{T, Vec{dim, T}}(t / norm(t))
• In the last four cases, pinv is reduced to inv.

One example use case for pinv of tensors is the elastic simulation of 3D trusses. In a truss element, the reference domain \xi is 1D and the nodal coordinate x is in 3D. Here, dx/d\xi is not a square matrix so it's not invertible. Then, pinv needs to be used.

What type of change is this?

• Bug fix in a backwards-compatible manner.
• New feature in a backwards-compatible manner.
• Breaking change: bug fix or new feature that involve incompatible API changes.
• Other (e.g. doc update, configuration, etc)

Checklist

• I ran all tests on my computer and it's all green (i.e. ] test).
• I have added tests that prove my fix is effective or that my feature works.
• I have added necessary documentation (if appropriate)