How to calculate area of space in Matalb

Dear members, I want to calculate area of space created by 4 lines as figure. Could you help me to do that ? Thank you

[Adam]

It rather depends how variable the 4 lines can be. In your case you just have the y origin and two vertical x limits so it is just an integration of your curve between those limits. If they were 4 arbitrary lines then it is a whole different matter.

doc cumtrapz

and similar functions should be about to do this easily enough for the specific case you show.

[Tran Hoa]

I will try. Thank a lot

[Image Analyst]

Is line #1 the blue curve, or the black top of the axes box?

[Tran Hoa]

Is the blue curve. Thank

Answer 1

[Image Analyst]

Try stacking the numerical row vectors of the curves vertically using a semicolon then use min() to get the lower-most curve:

bottomCurve = min([curve1; curve2; curve3; curve4; curve5; curve6], 1);

Then sum from the left index to the right index, whatever they are.

areaUnderCurve = sum(bottomCurve(index1 : index2))

[Tran Hoa]

Thank you