MATLAB: How to get equation from each plot

equationplot

So I have this code:
wkt is 117*1 array
x is also 117*1 array
a=polyfit(wkt,x);
b=polyval(a,wkt);
figure
plot (wkt,x)
hold on
plot (wkt,b)
Then I get a figure with 2 different plots. My problem is how to get the equation for each plot so I can evaluate the area between 2 curves. If I use this
a=trapz(wkt,x)-trapz(wkt,b)
will I get a correct result? Or is there another way? Thank you.

Best Answer

https://www.mathworks.com/help/matlab/ref/polyint.html polyint will integrate directly from the polynomial coefficients.
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