6楼: Originally posted by hzlhm at 2022-11-25 19:28:29
按x = exp(y) + 3*y代换，得到y值应为【-0.257627653049737，0.870573381315745】，而不是【-0.2576,1.6308】。...

  


x = exp(y) + 3*y
dx =  (exp(y) + 3)*dy

被积函数可转化成：
y*(exp(y) + 3*y)*t

y的积分区间：[-0.2576,1.6308]


F = @(t,y) y*(exp(y) + 3*y)*t;
Q = dblquad(F,0,5,-0.2576,1.6308)

Q = 106.8541

3楼: Originally posted by zyh700600 at 2022-11-24 22:42:52
x = exp(y) + 3*y
dx =  (exp(y) + 3)*dy

被积函数可转化成：
y*(exp(y) + 3*y)*t

y的积分区间：


F = @(t,y) y*(exp(y) + 3*y)*t;
Q = dblquad(F,0,5,-0.2576,1.6308)

Q = 106.8541


...

  

x = exp(y) + 3*y
dx =  (exp(y) + 3)*dy

被积函数可转化成：
y*(exp(y) + 3)*t

y的积分区间：[-0.2576,1.6308]

计算程序：

F = @(t,y) y*(exp(y) + 3)*t;
Q = dblquad(F,0,5,-0.2576,1.6308)

计算结果：
Q = 101.0479