Marking a specific point on a graph

I want to mark a point on my graph which is 63% from the starting point, but I also want the value of the point to appear on the graph as well, not just a marker.

Is there any way of doing this without manually working out what the value on X and Y should be and then manually entering them in?

[Jan]

What is "my graph", what is "the startpoint" and how do you determine "63% from the startpoint". What have you tried so far and what exatcly is your question? Do you have the wanted coordinates already and are looking for the text() command to insert a label?

[The Master of Matlab]

t1 = linspace (0, 120, 13)

v = [0 3.12 5.11 6.30 7.19 7.77 8.16 8.42 8.59 8.70 8.79 8.84 8.88];

plot(t1,v)

I would like to plot 63% from the start point which is 0 and I want this to appear on the graph not just a marker.

Answer 1

[KSSV]

x = rand(5,1) ;
y = rand(5,1) ;
plot(x,y,'.r') 
strx = num2str(x) ;
stry = num2str(y) ;
str = [strx,'',stry] ;
text(x,y,str) ;

doc text

[The Master of Matlab]

Doesn't help, but thanks.

Answer 2

[Star Strider]

Try this:

t1 = linspace(0, 120, 13);
v = [0 3.12 5.11 6.30 7.19 7.77 8.16 8.42 8.59 8.70 8.79 8.84 8.88];
v63 = 0.63*[max(v)-min(v)]+min(v);                                     % 63% Value
t63 = interp1(v, t1, v63);                                             % Time (‘Time Constant’)

figure(1)
plot(t1,v)
hold on
plot(xlim, v63*[1 1], '-r')
hold off
legend('Data', '63%', 'Location','E')
text(t63, v63, sprintf('v  = %6.2f\nt1 = %6.2f',v63, t63), 'VerticalAlignment','top')

[The Master of Matlab]

Thank you i'll give this a go.