Changing annotation size or font

Hello,

I'm having trouble fixing the annotations on my graph. For the annotations at the throat and exit, the value isn't that clear. Is there any reason why it's like this, and if I can change it so it's more clear? I've attached the code and a picture of my plot.

Thanks in advance

    plot(i,r1(l), '.b'); hold on
    plot(i,r2(l),'.b'); hold on
    yline(0,'-.k');
    xline(0,'-.r');
    xline(-L/2,'-.r');
    xline(L,'-.r');
    title ('Plot of Nozzle Shape');
    xlabel('Axial distance from the throat (mm)');
    ylabel('Radius (mm)');
    
    txt1 = ['Throat, d=' num2str(2*min(r1)) 'mm'];
    text(0,1,txt1);
    
    txt2 = ['Inlet, d=' num2str(2*r1(1)) 'mm'];
    text(-L/2,1,txt2);
    
    txt3 = ['Exit, d=' num2str(2*r1(end)) 'mm'];
    text(0.85*L,1,txt3)

Answer 1

[Mario Malic]

Is your piece of code in for loop?

Guessing that r1(1) and r1(end) are changing and there are many different texts on top of each other.

[Nadine Nassar]

Yes it is. But I thought using those commands will output the values when the for loop is finished. So what you're saying is that after every loop, it outputs r1(1) and r1(end)?

(Here's the loop btw)

l=0; %Defining the array

for i=(-L/2):2:L %Dividing the nozzle length into increments of 1, throat located at the centre
    
    l=l+1; %Adds new value to array
    
    r(l) =(r_throat^2)*(1 + (2.5*((i/L)^2))); %squared value of r from the equation of the nozzle
    r1(l) = sqrt(r(l)); %Positive value of r 
    r2(l) = -sqrt(r(l)); %Negative value of r 
    

end

[Mario Malic]

For the sake of people who are reading your code in future, please don't use lowercase character 'L' as your index, I thought it was number '1'.

Put this outside of for loop and it should work.

    txt1 = ['Throat, d=' num2str(2*min(r1)) 'mm'];
    text(0,1,txt1);
    
    txt2 = ['Inlet, d=' num2str(2*r1(1)) 'mm'];
    text(-L/2,1,txt2);
    
    txt3 = ['Exit, d=' num2str(2*r1(end)) 'mm'];
    text(0.85*L,1,txt3)

However, you should avoid using for loop here, and simplify your code. I think this would get you the same r you have at the end of your loop.

    i=(-L/2):2:L
    r=(r_throat^2)*(1 + (2.5*((i/L).^2)));

[Nadine Nassar]

Okay, i'll change it. I also tried your suggestion of not using a for loop and I got the same results, and realised the computational time was much faster this time. The text on the plot is also fixed now.

Thanks a lot for yor help

[Mario Malic]

Cool! You're welcome.