Basic Finite difference implementation for the visco(acoustic) wave equations

Input parameters are specified inside a sperate file "para.in".
A MATLAB script is used to generate a the model file.
The colormap used can be found here https://fr.mathworks.com/matlabcentral/fileexchange/25536-red-blue-colormap courtesy of Adam Auton.
Details are on the main file of the viscoacoustic code
Has not been tested on Octave.