Integration of functions of 1 and 2 vaiables

1 次查看（过去 30 天）

显示更早的评论

Ashok Das 2021-6-30

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/869148-integration-of-functions-of-1-and-2-vaiables

编辑： Amit Bhowmick 2021-7-1

I have two questions:

I have a function like this: f(x) = 1 (if x=0) and f(x)=0 (if x~=0). How can I integrate between any interval (a,b)?
Two-dimensional function: f(x,y) is given. How can I integrate f(x,y) with respect to only the variable 'x', while keeping 'y' fixed?

回答（1 个）

Amit Bhowmick 2021-7-1

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/869148-integration-of-functions-of-1-and-2-vaiables#answer_737363

You can use dirac function to define,

syms x

f=dirac(x)

intf=int(f,x) %Indefinite integration

intfd=int(f,x,[a b] %definite integration

2. For question 2 use this

syms x y

f=x^2+y^3

intf=int(f,x)

4 个评论
显示 2更早的评论隐藏 2更早的评论

Ashok Das 2021-7-1

That's what I am asking for. If we have to use "integral", then we have to make the function in the form

fun = @(x,y) ________

However, in my case the function is of not this form.

Can you give an example for this?

Thank you.

Amit Bhowmick 2021-7-1

编辑：Amit Bhowmick 2021-7-1

If you keep y fixed then it would be symbol only unless you provide some value of y. I think integral function does pure numerical integration (You can check reference page). hence it is not possible to integrate using integral where y is a symbol. So you can do one thing make an array of Y=a:b,

and put y=Y(ii) and then integrate using integral(f,ax,bx) where f=@(x) ax+by+c (say)

or use integral2(f,ax,bx,ay,by) f=@(x,y) ax+by+c

请先登录，再进行评论。

请先登录，再回答此问题。