Datatip not working. Changing location??

I cannot click on my graph for some wierd reason but whatever i just assumed i could use the datatip command to show the max of my graph.

When i wrote the code the location of DataTip changes for some wierd reason.

Any ideas?

I posted my code blow

heres the value of the variables

m0 = [ 41 91 331]

This is the frequency of the plot

f0 = [ 1 2 0.3]

This is the amplitude of the graph

This the command window it reads:

ans =

DataTip (X 0, Y 3.399e-16) with properties:

Why is it changing the location of the DataTip??

p= plot(f,P1);
m0=find(P1>0.1)
f0=P1(:,[m0])

datatip(p,f0,m0)

[Walter Roberson]

What is size(P1) ?

f0=P1(:,[m0])

implies it might have multiple rows. If P1 is not a row vector then find() is returning linear indexing not column indexing.

[John Emberson]

ans =

1 1001

result from size(P1)

i did it like that through my initial trial and error process and just never changed it back because

f0=P1([m0])

provides the same result as

f0=P1(:,[m0])

[John Emberson]

I also did transpose(P1) which resuluted in exactly the same thing.

Just incase it was becasue it was a problem with a column vector.

Also the problem is not with the results of find, its with datatip.

Find is finding the numbers i want.

F0 and m0 are the correct values. I am just trying to get them to showup on the graph because I keep having problems when i try to click on the graph. Unsure if its lag or what but I was jsut trying to use datatip to work around that.

Answer 1

[Walter Roberson]

You are passing in vectors of x and y coordinates, but datatip is only defined for scalar x and y.

In terms of your plot, f is your independent variable and P1 is your dependent variable. You are extracting some of the P1 entries and passing them in as x coordinates to datatip, and you are passing in indices as your y coordinates to datatip.

When you pass in x and y coordinates, datatip is defined to place the datatip at the nearest point to what you pass in.

You should be passing in f(m0(1)) as your x and f0(1) as your y to datatip()

[John Emberson]

So that kind of worked. I just make three different x variables and 3 different y variables and plugged into 3 data tips.

(41,1)

(91,2)

(331,0.3)

but now all three datatips state:

DataTip (X 90, Y 2) with properties:

DataIndex: 91

They are all plotting point 2 for some reason