MATLAB: Calculate area between y = 0 and the curve plotted by discontinuos data

calculate area between y = 0 and the curve ploted by discontinuos data

Hi,
I have a curve like graph. I want to calculate the area between y = 0 and the curve ploted by discontinuous data.
Could you have any suggestions?

Best Answer

As you have data (x,y) in your hand use trapz(x,y) (Trapezoidal numerical integration) to get the area. doc trapz..
Eg:
X = [0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.85];
rA = [-.0053, -.0052, -.0050, -.0045, -.0040, -.0033, -.0025, -.0018, -.00125, -.0010];
plot(X,-1./rA,'.-r')
% Area 
Int = trapz(X,rA)
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