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无限长弦的自由振动问题例1求解定解问题𝜕2𝑢𝜕𝑡2=𝑎2𝜕2𝑢𝜕𝑥2,−∞<𝑥<+∞,𝑡>0,(1)𝑢𝑡=0=𝜑𝑥,−∞<𝑥<+∞,(2)𝜕𝑢𝜕𝑡𝑡=0=𝑔𝑥,−∞<𝑥<+∞.(3)未知函数𝑢𝑥,𝑡有两个自变量𝑥和𝑡,我们应该取关于哪个自变量的Fourier变换呢?由Fourier变换的定义,应取关于变量𝒙的Fourier变换.(一)先确定对未知函数选取关于哪个自变量的Fourier变换.𝑢𝑥,𝑡𝑒−𝑖𝜔𝒙𝑑𝑥+∞−∞𝑉𝜔,𝑡F𝑢(𝑥,𝑡)==𝐺𝜔=F𝑔(𝑥)=𝑔𝑥𝑒−𝑖𝜔𝒙𝑑... 2024-05-203546.4 KB8页
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5.4.2DiagonalizationofRealSymmetricMatricesTheoremIfisaorderrealsymmetricmatrix,thereisaorthogonalmatrix,makes,whereisadiagonalmatrixwhosediagonalelementsareeigenvaluesof.ProofLine:Reviewfor𝑝𝑖1,𝑝𝑖2,⋯,𝑝𝑖𝑟𝑖⟶𝑞𝑖1,𝑞𝑖2,⋯,𝑞𝑖𝑟𝑖⟶𝑃=(𝑞11,𝑞12,⋯,𝑞1𝑟1,⋯⋯,𝑞𝑠1,𝑞𝑠2,⋯,𝑞𝑠𝑟𝑠).Diagonalizationofsymmetricmatrixusingorthogonalmatrix1.Findtheeigenvaluesofasymmetricmatrix;2.Findth... 2024-06-082351.41 KB12页
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