How to make the negative sign in the legend easier to see?

I generated the following legend in my plot but the negative sign ('-') is hard to see. I tried several different fonts but it didn't make a big difference. Is there any way to make it look better? For example, I'd like to make the negative sign "longer" and also get some space between "=" sign and the numbers.

The corresponding part of my code looks like this:

for idx = 1:length(sigma_d_list)
    sigma_d = sigma_d_list(idx)
    plot(x, y); hold on; 
    Legends{idx} = strcat('\delta_{d} =  ', ' ', num2str(sigma_d*1e3), ' mm'); 
end
xlabel('u (m)'); ylabel('PSF'); 
xlim([-0.5 0.5]*1e-4); 
lgnd = legend(Legends); 
set(lgnd, 'FontSize', 14); 
set(lgnd, 'FontName', 'Times New Roman'); 

Answer 1

[Jan]

strcat removes interior spaces. This is not useful here and it is not in general. I consider this as a design error.

Use cat instead:

Legends{idx} = cat(2, '\delta_{d} =  ', ' ', num2str(sigma_d*1e3), ' mm');
% or
Legends{idx} = ['\delta_{d} =  ', ' ', num2str(sigma_d*1e3), ' mm'];

Do you really want 3 spaces? Or was this a try to struggle with the smart deblanking of strcat?

I'm not a fan of num2str also, which calls sprintf internally. Just call it directly:

Legends{idx} = sprintf('\\delta_{d} = %g mm', sigma_d * 1e3);

Nicer, faster and less confusing.

[Daigo]

Thanks, Jan! I only needed 1 space. Your method perfectly works for me.

How about the font of the negative sign? The current one looks too short (it almost looks like a dot...), and it does not look so good even with a space. Do you know any fonts which makes it look longer?

[Jan]

What about:

plot(1:10)
legend({'$\delta_{d} = -0.5$'}, 'Interpreter', 'latex')

[Bruno Luong]

If not enough

figure; plot(123+zeros(1,10))
legend('$\delta_{d} = $ {\fontsize{50}{60}\selectfont -} $123$', 'Interpreter', 'LaTex')

legend('$\delta_{d} = $ {\fontsize{50}{60}\selectfont \bf -} $123$', 'Interpreter', 'LaTex')

[Daigo]

@Jan Thanks Jan! That looks perfect!

[Daigo]

@Bruno Luong Aha, you can set such a fine-grained font format! Thanks for your tip!

Answer 2

[Voss]

You can get some more space by using cell arrays in strcat (because strcat trims white space off the ends of character arrays):

Legends{idx} = strcat({'\delta_{d} =  '}, {' '}, num2str(sigma_d*1e3), ' mm');

[Daigo]

Thanks, Benjamin!