Integration in matlab: Explicit integral could not be found

2 次查看（过去 30 天）
satendra kumar
satendra kumar 2012-12-8
H=1,R=1,theta=20;
syms x;
syms alpha;
%sigma=F/(2*pi*R*(alpha-1));
z_desh=((x/alpha*x^2+1-alpha)^2-1)^-.5
beta=(sin(theta)+(sin(theta)*sin(theta)+4*alpha*(alpha-1)))/2*alpha
eq=int(z_desh,x,4,1)
when i run the above code en error show like: Warning: Explicit integral could not be found. How to solve this.?
Thanks

请先登录，再回答此问题。

采纳的回答

Walter Roberson
Walter Roberson 2012-12-8
First thing to do is heck whether the x/alpha*x^2 is really what you meant. If it was, why not say x^3/alpha ?
Next, check whether you really want to integrate from 4 down to 1, instead of from 1 to 4.
Thirdly, check why you define beta but then do not use it in what is being integrated.
If your integral is exactly as shown, then there is no readily available analytic form for it. A small number of values of alpha lead to analytic forms; the others do not.
  8 个评论
显示 6更早的评论
Walter Roberson
Walter Roberson 2012-12-8
My code is in Maple, using a facility of Maple that does not translate directly into the MuPAD Symbolic Toolbox
What I determined in the end is that you had better use numeric integration and something like fsolve(), instead of trying to use symbolic integration.
When you do your fsolve(), do not use an alpha less than 1: it is not difficult to demonstrate that alpha between 0 and 1 will generate integrals involving complex values.

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Functional Programming 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