“…In the general case, it is also solved numerically and determines parameter t, which enters into the system (11) Considering Y 11 and Y 31 to have been found at the previous state of integrating (8), from the second equation (11) via integration and uncomplicated transformations, we find (12) In particular case (9), when the solution to the aux iliary problems is written in explicit form, parameter t, which determined the angle of inclination of the first dispersion curve, is also found in explicit form, and is expressed through the variable Young's modulus: (13) which in fact characterizes the pivotal mode for the waveguide with variable elastic properties.…”