Highlighten specific x-axis values

Hey guys !

I need some help to plot a small figure for my thesis. I think the question is quite simple but however I have not found a solution yet...

What I want to do is to plot my figure with its x-axis that ranges from 0 to 5 in steps of 0.5. Now I want to add 2 specific values (say 1.1 and 3.387) to the x-axis and label them as f_1 and f_2. I tried using xtick but it did not work. Here's my code:

% Values
x_max = 0.22;
v_max = 1.6;
a_max = 35;

f_1 = v_max/(x_max*2*pi);
f_2 = a_max/(v_max*2*pi);

a_1 = x_max * (2*pi*f_1)^2;
a_2 = a_max;

% Curves
f_c1 = [0 f_1];
y_c1 = [0 a_1];

f_c2 = [f_1 f_2];
y_c2 = [a_1 a_2];

f_c3 = [f_2 5];
y_c3 = [a_max a_max];

% Plot
figure
hold on
grid on
box on

xlabel('Frequency [Hz]')
ylabel('Acceleration [m/s^2]')
title('Dynamic Operating Space')
set(gca,'xtick', [f_1 f_2], 'xticklabel', {'f_1'; 'f_2'})

% Characteristic Frequencies
plot([f_1 f_1], [0 40], '--', 'color', 'red')
plot([f_2 f_2], [0 40], '--', 'color', 'red')

% Dynamic Curves
plot(f_c1, y_c1, 'LineWidth', 2, 'color', 'black')
plot(f_c2, y_c2, 'LineWidth', 2, 'color', 'black')
plot(f_c3, y_c3, 'LineWidth', 2, 'color', 'black')

an_1 = text(0.3, 5.5,'x_{max} = 0.22m');
set(an_1,'Rotation',45)
%set(an_1,'FontSize',12)
% ar_1 = area(f_c1, y_c1);
% set(ar_1, 'FaceColor', [1 0.5 0]);

an_2 = text(2, 22.5,'v_{max} = 1.6m/s');
set(an_2,'Rotation',45)

an_3 = text(4, 36.5,'a_{max} = 35m/s^2');

This is what I got:

If the x-axis would now display the full range in addition to above f_1 and f_2 I'd be very happy.

Any clue ?

Additionally, is there any way to grey out the area under the curves ?

Thank you !

[darova]

If you want to see numbers just don't force MATLAB to display symbols

set(gca,'xtick', [f_1 f_2])%, 'xticklabel', {'f_1'; 'f_2'})

To paint some area use patch

[Aladin Djuhera]

Hi ! Thank you, but I would not like to see the actual numbers but rather the text f_1 and f_2. Is that possible ?

[darova]

This is what your code produces on my PC

Answer 1

[Adam Danz]

"What I want to do is to plot my figure with its x-axis that ranges from 0 to 5 in steps of 0.5. Now I want to add 2 specific values (say 1.1 and 3.387) to the x-axis and label them as f_1 and f_2."

If you want all ticks 0 : 0.5 : 5 and also the values in f_1 and f_2,

xtickVals = unique([0 : 0.5 : 5, f_1, f_2]);
xtickLabs = compose('%.3g',xtickVals);
xtickLabs(ismembertol(xtickVals,[f_1,f_2])) = {'f_1','f_2'}; 
set(gca,'xtick', xtickVals, 'xticklabel', xtickLabs, 'xlim', [min(xtickVals),max(xtickVals)])

If you want only the f_1 and f_2 labels,

set(gca,'xtick', [f_1, f_2], 'xticklabel', {'f_1','f_2'}, 'xlim', [0,5])

A better idea might be to use xline() to label those values.

set(gca,'xtick', 0 : 0.5 : 5, 'xlim', [0,5])
xline(f_1,'--r','f_1','LabelVerticalAlignment','bottom')
xline(f_2,'--r','f_2','LabelVerticalAlignment','bottom')

Finally, if you want the underscrore rather than a subscript, set the interpreter to none.

xline(f_1,'--r','f_1','LabelVerticalAlignment','bottom','Interpreter','None')

[Aladin Djuhera]

Hi ! Thank you very much. This comes really close to my problem. I am already happy with it but is there a way to rotate the f_1 ? So it is straight and not turned ?

Note that there was a ',' missing for future reads on this question:

set(gca,'xtick', 0 : 0.5 : 5  ,  'xlim', [0,5])
xline(f_1,'--r','f_1','LabelVerticalAlignment','bottom')
xline(f_2,'--r','f_2','LabelVerticalAlignment','bottom')

[Adam Danz]

Thanks, I fixed that typo.

To rotate the label, see the LabelOrientation property of xline().

https://www.mathworks.com/help/matlab/ref/xline.html#mw_b6cfa511-98d7-4866-aaf6-009bde12c995

[Aladin Djuhera]

Perfect! Thank you very much, Adam :)