By default, MATLAB supports a subset of TeX markup. For a list of supported symbols, see the documentation . For more symbols, you can use LaTeX markup by setting the Interpreter property to 'latex'. Use dollar symbols around the text. For example:
title('$\hat{\psi}$','Interpreter','latex')
If you are using the legend function in R2018a or earlier, you must specify the labels as a cell array to distinguish the labels from the name-value pairs. In R2018b and later, the cell array is not needed.
plot(1:10)
legend({'$\hat{\psi}$'},'Interpreter','latex')
legend('$\hat{\psi}$','Interpreter','latex')
When you use LaTeX markup, the displayed text uses the default LaTeX font style. The FontName, FontWeight, and FontAngle properties no longer have an effect. To change the font style, use LaTeX markup instead.
For more information about using LaTeX, Refer to the documentation: