How to numerically integrate a non-integer (using trapz)

Question

Brian Peoples 2019-4-3

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/454096-how-to-numerically-integrate-a-non-integer-using-trapz

回答： Walter Roberson 2019-4-3

In this case im trying to get F(i) with the given inputs:

kp = -25
ki = 10
theta(i) = .314 or something thats not an integer
t = .01
         F(i) = kp*theta(i) + ki.*trapz(t,theta(i))

This will not run because theta(i) is not an integer... I'm using radians that change in each iteration of a loop. Any ideas?

Regards,

Brian Peoples

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2019-4-3

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/454096-how-to-numerically-integrate-a-non-integer-using-trapz#answer_368799

When you use trapz() and supply a scalar second argument but no third argument, trapz() always interprets the argument as a dimension number. If you do not want it to be a dimension number then you must supply a third parameter containing the dimension number.

If you are trying to supply theta(i) as the spacing between points, then it would need to go as the first parameter.

Your likely mistake is in trying to call trapz() on one y point at a time. You should put all of the x and y into vectors first, and then use a single trapz() call.