computing area between 2 curves
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I have two curves from the 2 vetctors as a result of simulation. I want to find the area between these 2 curves. The curves are intersecting many times.
any ideas are appreciated!!
采纳的回答
AC
2012-7-4
Hi,
From scratch, you could try something like:
1/2*(abs(C1(2:end)-C2(2:end))+abs(C1(1:end-1)-C2(1:end-1)))*diff(I)'
where C1 and C2 are your curves and I the x-axis.
This will give you an estimate of the integral of C1(t)-C2(t) dt for t in I.
Cheers,
AC
更多回答（1 个）
Luffy
2012-7-3
If u know the vectors then try using polyarea & subtract them
3 个评论
Vijay
2012-7-3
Luffy
2012-7-4
I put too much thought into it,ws thinking about finding area covered by each curve with x axis and then subtracting them to get area between them.
Happy to know polyarea helped you
AC
2012-7-4
Hi,
Substracting the two areas is ok if the curves don't cross and you substract in the right order (that is: highest - lowest). Otherwise you will end up with a wrong result. For example, take sin(x) and cos(x) between 0 and 2: int cos(t)-sin(t) dt = -0.5 approx. int abs(cos(t)-sin(t)) dt= 1.33 approx.
It's the second one that you want. So you should compute the area of the difference in absolute value (see my response below). Cheers,
AC
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