How to find the double trapezoidal integral of a function with 3 variables

Question

Trond Oesten 2015-5-8

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/215692-how-to-find-the-double-trapezoidal-integral-of-a-function-with-3-variables

回答： Torsten 2015-5-8

Hi,

I have a function with 3 variables that I want to find the trapezoidal double integral of. My answer should be dependent on the last variable. I have tried using trapz, but I only get it to work when I give the undefined variable a value. Is there a way to use trapz in matlab, and still have an answer that is dependent on a variable?

Thanks!

Script:

clc; clear all; close all;
syms x
D1 = 0:1:3000;
D2 = 0:1:400;
[d1,d2] = meshgrid(D1,D2);
my_function = (d2./d1).*(x./d1).^(d2-1).*exp(-(x./d1).^d2)+((d2./d1)+d1.^2);
d = trapz(D2,trapz(D1,my_function,2))