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Wolfram mathematica 求解微分方程-Wolfram Alpha与Mathematica,不同的结果_Wolfram Mathematica_Differential Equations_Wolframalpha - Fatal编程技术网

Wolfram mathematica 求解微分方程-Wolfram Alpha与Mathematica,不同的结果

Wolfram mathematica 求解微分方程-Wolfram Alpha与Mathematica,不同的结果,wolfram-mathematica,differential-equations,wolframalpha,Wolfram Mathematica,Differential Equations,Wolframalpha,我在用数学解一个微分方程。以下是我要解决的问题: DSolve[{-(r V[w])+u V'[w]+s V''[w]==-E^(g w)},V[w],w] 当我使用Wolfram Alpha解决它时,它给了我一个很好的解决方案: solve u*V'(w) + s*V''(w) - r * V = -exp(g*w) V(w) = c_1 e^((w (-sqrt(4 r s+u^2)-u))/(2 s))+c_2 e^((w (sqrt(4 r s+u^2)-u))/(2 s))+e^(g

我在用数学解一个微分方程。以下是我要解决的问题:

DSolve[{-(r V[w])+u V'[w]+s V''[w]==-E^(g w)},V[w],w]
当我使用Wolfram Alpha解决它时,它给了我一个很好的解决方案:

solve u*V'(w) + s*V''(w) - r * V = -exp(g*w)
V(w) = c_1 e^((w (-sqrt(4 r s+u^2)-u))/(2 s))+c_2 e^((w (sqrt(4 r s+u^2)-u))/(2 s))+e^(g w)/(r-g (g s+u))
但当我使用Mathematica时,解决方案又长又难看:

{{V[w]->(2s(2e^((2gs+u-Sqrt[4rs+u^2])w)/( 2s)+(-u+Sqrt[4rs+u^2])w/(2s))gs- 2 E^((-u-Sqrt[4 r s+u^2])w)/( 2s)+(2gs+u+Sqrt[4rs+u^2])w/(2s))gs+ ((2gs+u-Sqrt[4rs+u^2])w)/( 2s)+(-u+Sqrt[4rs+u^2])w/(2s))u- E^((-u-Sqrt[4 r s+u^2])w)/( 2s)+(2gs+u+Sqrt[4rs+u^2])w/(2s))u+ ((2gs+u-Sqrt[4rs+u^2])w)/( 2s)+(-u+Sqrt[4rs+u^2])w/(2s)Sqrt[ 4 r s+u^2]+ E^((-u-Sqrt[4 r s+u^2])w)/( 2s)+(2gs+u+Sqrt[4rs+u^2])w/(2s)Sqrt[ 4 r s+u^2])/(Sqrt[ 4RS+u^2](-2GS-u+Sqrt[4RS+u^2])(2GS+u+ Sqrt[4 r s+u^2])+ E^((-u-Sqrt[4rs+u^2])w/(2s))C[1]+ E^((-u+Sqrt[4rs+u^2])w/(2s))C[2]}

哎哟!

总的来说,我希望Mathematica给我一个很好的解决方案,就像Wolfram Alpha那样。有人知道我失踪了吗?还是我做错了?谢谢

简化[DSolve[{-(rv[w])+uv'[w]+sv'[w]=-E^(gw)},V[w],w]


Simplify是你的朋友

对,当然,谢谢!出于某种原因,它并没有一路简化。也许Mathematica需要一些我忽略的条件。编辑:或者这就是Mathematica认为的“一路简化”。