Two-point tensor

They are used in continuum mechanics to transform between reference ("material") and present ("configuration") coordinates.

[1] Examples include the deformation gradient and the first Piola–Kirchhoff stress tensor.

As with many applications of tensors, Einstein summation notation is frequently used.

Thus, a two-point tensor will have one capital and one lower-case index; for example, AjM.

In contrast, a two-point tensor transforms vectors from one coordinate system to another.