Calculate the area under a curve with Matlab

[aslfd]

Hello,

I have a table (x,y) contains 2020 measured values (stroke sensor). I would like to calculate the area under the curve. Can i do it with Matlab(or Excel).


Thanks

 

[xnuke]

Yes, and yes.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[GregLocock]

I don't know if you can. I can.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[IRstuff]

Wikipedia can, too:

https://en.wikipedia.org/wiki/Trapezoidal_rule

https://en.wikipedia.org/wiki/Simpson's_rule

https://en.wikipedia.org/wiki/Numerical_integration

Now, you just need to decide what accuracy you need.

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //

http://www.engineering.com/AskForum/aff/32.aspx

faq731-376 forum1529

 

[aslfd]

Thanks

 

[cibachrome]

Compute the area ABOVE the curve from the total area of the graph paper and subtract it.

Print the figure and cut out the area of the graph and weight it on a precision scale. Cut out a 1 cm by 1 cm piece of paper and weigh it also. Use the scale factor (gram crackers per square cm) to figure out the area under the curve.

Digitize the curve and fit it to a series of very small straight lines. Then integrate it using the ani-Cramer vs. Cramer rule.

Use the built in functions in Lotus 1-2-3 to compute the area and save it as a .csv file. Import that into Excel and the answer will be in the 'Answer' worksheet tab.

Double integrate the curve and take the first differential.

Use the lsqcurvefit function (Optimization Toolbox) to fit the digitized curve to a mass spring damper Simulink model. Then use an integrater to perform the calculation.

That's enough for now, my candlestick phone is ringing..