例181求泛函=/xy/d在边界条件 (0)有界,y(1)=0 和约束条件xy2d=1下的极值曲线 解】采用上面描述的 lagrange乘子法,可以得 到必要条件Isoperimetric Problem (continued) Variational Formulism of Differential Equation (Approximation Method (Rayleigh-Ritz) Examples ~18.1 ¦¼ I[y] = Z 1 0 xy02 dx 3>.^‡ y(0)k., y(1) = 0 Úå^‡ Z 1 0 xy2dx = 1 e4Š­‚ =)>æ^þ¡£ãLagrange¦f{§Œ± 7‡^‡  ∂ ∂y − d dx ∂ ∂y0 ￾ xy02 − λxy2
= 0 = d dx  x dy dx  + λxy = 0 C. S. Wu 1›lù C©{ÐÚ