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Extraction of values from a graph.

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I have drawn a graph witha a few known values. I need the values of the intermediate x-values. The code is as below.
T=20:20:300;
rho=[1000 995 985 974 961 945 928 909 889 867 842 815 786 752 714];
plot(T,rho)
From the above plotted graph I need values of T which are not defined.
If there is any other method through which I can extract values(Not necessarily from the graph like linear interpolation), please do tell.
Thank You.

Accepted Answer

J. Alex Lee
J. Alex Lee on 25 Dec 2019
There is a function called "interp1", which seems like it will suit your need. You have options on interpolation method.
T=20:20:300;
rho=[1000 995 985 974 961 945 928 909 889 867 842 815 786 752 714];
plot(T,rho,'.-')
% T values of interest
Ti = [25 56 88 204 288]
rhoi = interp1(T,rho,Ti)
hold on;
plot(Ti,rhoi,'*r')
  3 Comments
J. Alex Lee
J. Alex Lee on 25 Dec 2019
What do you intend with this line of code:
Ti=20:1000:300;
Uncomment to see the result. You are asking just for the number 20.
If you want 1000 points between 20 and 300 spaced evenly, then do
Ti = linspace(20,300,1000);
Lepakshi Ramkiran
Lepakshi Ramkiran on 25 Dec 2019
yea my bad sorry, got confused.
Thanks. got it.

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