Getting 0 when using quad

7 次查看（过去 30 天）
Aldo
Aldo 2016-11-11
评论： Walter Roberson 2016-11-11
fun = @(x) 80*exp(-((x-pi)/0.002).^2);
I = quad(fun,0,6)
I2= integral(fun,0,6)
I =
0
I2 =
1.464129900321425e-69
Why do I get 0 when using quad?
Best regards Aldo

请先登录，再回答此问题。

回答（2 个）

Walter Roberson
Walter Roberson 2016-11-11
编辑：Walter Roberson 2016-11-11
The two use different adaptive techniques. The function has a sharp peak at Pi and one technique misses it completely and the other barely catches it. The actual integral over that range is (2/25*(erf(500*Pi)+erf(3000-500*Pi)))*sqrt(Pi) which is about 0.284
To get a better answer:
integral(fun,0,6,'Waypoints', pi)
  2 个评论
Aldo
Aldo 2016-11-11
And how should you go about to solve it with Quad?
Walter Roberson
Walter Roberson 2016-11-11
I wouldn't solve it with quad(). I might solve it with quadgk
quadgk(fun,0,6, 'waypoints', pi)

请先登录，再进行评论。

KSSV
KSSV 2016-11-11
You are trying to calculate the area under the curve as shown in the attached image. See the values on the axes, so I think getting zero is legitimate.

类别

在 Help Center 和 File Exchange 中查找有关 Marine and Underwater Vehicles 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by