function [ S1, S2, S3, T12, T23, T13 ] = PrnStresses (Sx, Sy, Sz, Txy, Tyz, Tzx)
%
%  This function uses applied stresses to compute the pricipal stresses 
%  and shears.  The maximum principal stress is S1 and the maximum
%  principal shear is T13.
%
%  Input
%    Sx, Sy, Sz       the applied normal stresses
%    Txy, Tyz, Tzs    the applied shear stresses
%
%  Output
%    S1, S2, S3        the principal stresses
%    T12, T23, T13     the principal shear stresses


%  Compute the roots of the polynomial


%  Arrange in order


end