This code enables dispersion analysis of guided waves in a fluid-solid bilayer. Running this code without modifications, it shows phase velocity dispersion curve of anti-symmetric guided wave when fluid thickness
(PEG-400) increases from 0 to 250 micrometres @ f= 9.71 MHz. This result is presented and analysed in the following paper "Holographic Detection of Nanoparticles using Acoustically Actuated Nanolenses"
and written by Aniruddha Ray, Muhammad Arslan Khalid, Andriejus Demcenko, Mustafa Daloglu, Derek Tseng, Julien Reboud, Jonathan Cooper, and Aydogan
Ozcan, see Nature Communications 2019.

A theoretical framework is provided in the following paper "Guided waves in a fluid-solid bilayer" 
and written by Carlos L.Yapura and Vikram K.Kinra. This paper can be find under the following link: https://doi.org/10.1016/0165-2125(94)00043-5.

The code is developed and implemented by A. Demcenko 2017. The last check of this code was performed using Matlab R2018a on the 2nd December 2019. Tu run the code in Matlab, please, type start_dispersion_analysis and press Enter.