You can use hold method to retain the current plot while adding new plot. Legend method to add legends to axes
Here is an example of retaining legend on the axes while calling function to plot new data
function my_plot(x,y,legendName)
plot(x,y,'DisplayName',legendName);
legend
end
x=linspace(1,10);
y=x*2;
y1=x*3;
y2=x*4;
my_plot(x,y,'x*2');
hold on
my_plot(x,y1,'x*3');
my_plot(x,y2,'x*4');
hold off
Hope this helps!
