numerical integration __ integral limits being variables
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Hello, I want to numerically integrate functions whose upper limits x, lower limits 0. Say;
int_0^x f(x) dx
Which method should I use. trapz, simpson, or omething else and which command ?
I mean can you send a simple example of doing this please? Thanks
采纳的回答
Roger Stafford
2015-4-5
There are a number of ways you can proceed. One way is to use 'int' with a variable upper limit. See:
http://www.mathworks.com/help/symbolic/int.html
If that does not succeed (which often happens) you can do numerical integration using the 'cumtrapz' function which also allows you to have a variable, though discrete, upper limit. See
http://www.mathworks.com/help/matlab/ref/cumtrapz.html
Finally, there are several functions in the File Exchange which are numerical but have higher precision. I wrote one of these. It is located at:
http://www.mathworks.com/matlabcentral/fileexchange/19152-cumulative-cubic-integration
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Star Strider
2015-4-5
1 个投票
If you are numerically integrating functions, use integral (or quad and its friends if you don’t have integral). You will obviously have to define what value ‘x’ is to do a numerical integration.
If you want to do a symbolic integration (and your function is integrable), use the Symbolic Math Toolbox int function.
3 个评论
Meva
2015-4-5
Star Strider
2015-4-5
You can use cumtrapz with data returned by your function, but not with your function itself. If you want to use a function, you have to use integral or quad, as I wrote before.
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