computing area between 2 curves

3 次查看(过去 30 天)
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
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
  4 个评论
Luffy
Luffy 2012-7-9
see doc diff
If X is a vector, then diff(X) returns a vector, one element shorter than X, of differences between adjacent elements.
Vijay
Vijay 2012-7-23
if X is a vector from 1:10 say X-axis. then diff(X) is a vector of '1' nine times. What is the use of multiplying it??

请先登录,再进行评论。

更多回答(1 个)

Luffy
Luffy 2012-7-3
If u know the vectors then try using polyarea & subtract them
  3 个评论
Luffy
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
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

请先登录,再进行评论。

类别

Help CenterFile Exchange 中查找有关 Vibration Analysis 的更多信息

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by