How to get area under the fit attained by Curve Fitting tool?

Here I have two data arrays namely t and T. I have used the command

t = linspace(0,270,10)
T = [30 32 34.5 38.6 40 40 42 42.5 42.5 42 41.5]
cftool(t,T)

And the cftool gui to attain the following:

I want to get the area under the curve from (t=0) to (t=180). What should I use in this case. I am a complete novice to MATLAB and I do most of my work using the GUI. If anyone can help me it will be really appreciated.

Answer 1

[Alan Stevens]

Try

help trapz

Answer 2

[Sam Chak]

Hi @Anik Mukhopadhyay

You can check if this works:

t = linspace(0, 270, 10);
T = [30 32 34.5 38.6 40 42 42.5 42.5 42 41.5];

% Create a shape-preserving piecewise interpolation from t = 0 to 180
tnew = 0:0.01:180;
pch = interp1 (t, T, tnew, "pchip");

plot(t, T, 'ro', tnew, pch, 'b-', 'linewidth', 1.5)
grid on
xlabel('t')
ylabel('T')

Area_under_blue = trapz(tnew, pch)

[Sam Chak]

This is a rough estimation:

Areas of a Triangle plus a Rectangle:

(30 + 42)*150/2 + (180 - 150)*42

ans = 6660