C-eigenvalue inclusion theorems for piezoelectric-type tensors

C-eigenvalues and C-eigenvectors of piezoelectric-type tensors play an important role in piezoelectric effect and converse piezoelectric effect. In this article, with the help of components of C-eigenvectors, we present three inclusion theorems to locate all C-eigenvalues for a given piezoelectric-type tensor. Finally, numerical examples are reported to be tighter than the S-partition method presented by Li and Li (2017).