How can I solve a sum of two variables function?

2 次查看（过去 30 天）

显示更早的评论

3Nz0 2021-2-24

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/754999-how-can-i-solve-a-sum-of-two-variables-function

评论： Walter Roberson 2021-3-4

Hello.

I have a two variables function: f=U(t,M).

I need to solve the integral (from 0 to +Inf) in dlnM of the following sum:

F(t,M) = sum(i odd) (1/i^2)*exp(-i^2 * U(t,M))

If anyone can help me, I will be appreciate it.

Thank you

5 个评论
显示 3更早的评论隐藏 3更早的评论

3Nz0 2021-3-4

I have the expression of U(t, M). t and M are two vectors. I solved the problem discretizing the function, so U is a matrix. However I need to a function because 1)I want to estimate some parameters with fminsearch() 2)the result from integral with Simpson or traps method is a little bit higher then the desired results. Thank you, again

Walter Roberson 2021-3-4

If M is a vector then you cannot integrate with respect to M.

At present, you have no hope of getting a closed form integral as long as you leave U as an indefinite function. If you put in the actual definition for U then you might get a useful result, perhaps. I was recently assisting someone with a broadly similar expression in which it turned out that what they were doing could be written in terms of JacobiTheta4.

请先登录，再进行评论。

请先登录，再回答此问题。