I understand the issue that you are encountering here in labeling the y-axis in the MATLAB plots.
The issue is that LaTeX commands like '\widetilde' weren't enclosed in dollar signs ($) and MATLAB wasn't set to interpret labels with LaTeX.
You can refer to the below mentioned code snippet and the attached output for better understanding:
plot(r, v1_lower, r, v1_upper, 'LineWidth', 2);
xlabel('r');
ylabel('$\widetilde{\nu}_1(\chi ,\tau ;r )$', 'Interpreter', 'latex');
title('Plot of $\widetilde{\nu}_1$', 'Interpreter', 'latex');
legend('Lower', 'Upper');
Output:
To learn more about using LaTex to format titles and axis labels, you can refer to the following documentation:
Hope this helps!
