D'Alembert solution with fixed ends
For u_tt=c²u_xx with zero ends on [0,L], extend initial displacement f and velocity g oddly with period 2L to F,G.
Key knowledge
For u_tt=c²u_xx with zero ends on [0,L], extend initial displacement f and velocity g oddly with period 2L to F,G. Then u(x,t)=[F(x−ct)+F(x+ct)]/2+(1/(2c))∫x−ctˣ⁺ᶜᵗG(s)ds.
Conditions and scope
- c,L>0; sufficiently smooth compatible data give a classical solution.
- Using the original f,g outside [0,L] instead of their extensions generally breaks the fixed-end conditions.
Sources · 1
References
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Evidence and review
Section 4.8.2 formula and section 4.8.3 extension warning.
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Entry details
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- University core expansion