A DIRECT FORMULATION FOR THE STRETCH TENSOR

The square root of a positive definite symmetric tenser can be evaluat ed in two different ways: tile first involves the calculation of eigen values and eigenvectors and the second is based on the determination t he square root as a polynomial expression of the tenser itself. Using the second method, the N-dimensional case is studied and, in particula r, up to four-dimensional case, the principal invariants of the square root tenser which appear in the polynomial coefficients are presented in terms of the tenser's principal invariants.