# parametric plot with values of parameter on plot

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Mohsen on 18 Mar 2014
Answered: mehran on 20 Sep 2023
I want to graph x=f(t) and y=g(t) but I want some sampling of values of t on the graph. Is there an option of plot command or a specialized program for doing this? So for example say x=cos(t), y=sin(t). I want to annotate the graph by putting t=0, t=pi/6, t=pi/4, etc on the graph. Of course this can be done by adding many text boxes to the graph but I was looking for a more automated solution.
Salaheddin Hosseinzadeh on 19 Mar 2014
Oh! Now I see what you're looking for. Unfortunately I don't know about an automated solution, all I can think of, is to write my own code to add annotations or text to the graph! But I don't think if that's gonna be ver usefull and beneficial code for me! :(
Sorry!

Mischa Kim on 19 Mar 2014
Edited: Mischa Kim on 19 Mar 2014
Mohsen, would this do (using ticks and tick labels)?
t = -pi:.1:pi;
y = sin(t);
plot(t,y)
set(gca,'XTick',-pi:pi/2:pi)
set(gca,'XTickLabel',{'t=-pi','t=-pi/2','t=0','t=pi/2','t=pi'})
Mohsen on 19 Mar 2014
The labels are to be on the graph, not on the axis. So for example x= cos(t) y= sin(t) will make a circle and on various points of the circle we want to write the value of parameter t. In general x=f(t), y=g(t) and t has a range of values. We want the the t values on the (x,y) plot.

mehran on 20 Sep 2023
t = linspace(0, 10*pi, 500);
x = 3*t.*cos(t);
y = 3*t.*sin(t);
figure(3);
plot(x,y);
hold on;
vec1=1:20:floor(length(t)/2);
vec2=floor(length(t)/2)+1:10:length(t);
vec=[vec1 vec2];
for ii = 1:length(vec)
txt=sprintf('t=%4.2f',t(ii));
text(x(vec(ii)), y(vec(ii)),txt, 'HorizontalAlignment','left');
end
xlabel('x');
ylabel('y');
title('spiral parametric curve with sample parameter values shown')

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