changing the legend line style (":","-","--","-.") for 4 black lines in plot instead of using multip colour

What should i add to appear the different black line style

figure; 
plot([1:M]/M,u,'DisplayName','M='+string(M),'LineWidth',1); hold on;
xlabel('i/M','FontWeight','bold','FontSize',12);
ylabel('U','FontWeight','bold','FontSize',12); 
lgd=legend;
lgd.NumColumns = 1;
lgd.FontSize = 12;
ax = gca;
ax.XAxis.FontWeight = 'bold';
ax.YAxis.FontWeight = 'bold';

[Jan]

Hint: [1:M] concatenates the vector 1:M with nothing. Slightly faster: (1:M) / M

Answer 1

[Jan]

figure;
axes('NextPlot', 'add', ...
    'LineStyleOrder', cellstr([":", "-", "--", "-."]), ...
    'ColorOrder', zeros(1, 3));
plot(rand(10, 4))
legend

[NOUFA]

Thanks that really helpful