level 2
shiwu之歌
楼主
soltest是得到的待定系数的解，其中第一个参数k的值先代入一个常微分非常求解，之后得到的函数和剩下的解代入到设的函数里面，我尝试一块代入，要不出错，要不有些没被替换
soltest = {{k -> c/q, a0 -> 0, a1 -> -1, b1 -> 0, c0 -> c/q, c1 -> 0,
c2 -> 1, d1 -> 0, d2 -> 0}, {k -> (4 c)/q, a0 -> 0, a1 -> -(1/2),
b1 -> 0, c0 -> (2 c)/q, c1 -> 0, c2 -> 1/2, d1 -> 0, d2 -> 0}};
odesol = Assuming[
{k /. soltest[[1]], c > 0, q > 0},
sol = DSolve[{y'[x] == k + y[x]^2, y[0] == 0},
y[x], x]
] /. y -> P
U[x_] := a0 + a1*P[x] + b1*P[x]^(-1) /. {soltest[[1]], odesol[[1]]}
U[x]
2024年02月08日 13点02分
1
soltest = {{k -> c/q, a0 -> 0, a1 -> -1, b1 -> 0, c0 -> c/q, c1 -> 0,c2 -> 1, d1 -> 0, d2 -> 0}, {k -> (4 c)/q, a0 -> 0, a1 -> -(1/2),
b1 -> 0, c0 -> (2 c)/q, c1 -> 0, c2 -> 1/2, d1 -> 0, d2 -> 0}};
odesol = Assuming[
{k /. soltest[[1]], c > 0, q > 0},
sol = DSolve[{y'[x] == k + y[x]^2, y[0] == 0},
y[x], x]
] /. y -> P
U[x_] := a0 + a1*P[x] + b1*P[x]^(-1) /. {soltest[[1]], odesol[[1]]}
U[x]
