[理工] [工數]-邊界直問題~
先問一題BESSEL ..
1.
2 2
x y'' - 2xy' - (x - 2)y = 0
答案
y = c1 xcoshx + c2 xsinhx
但是我的答案是
3 3
--- ---
2 2
y = A1 x I (x) + A2 x K (x)
1 1
--- ---
2 2
請問我這達按跟解答有一樣嗎..
2.
Find eigenvalues and eigenfunctions of
y'' - 5y' + Qy = 0 , 0<x<pi , y(0)=0 , y(pi) = 0
痾 這題其實 我只是想要問...
--------
+ |
5 \| 25-4Q
-
-----------------
2
這要怎麼變成 y 阿..
應該說怎麼看 比較清楚.. "Q = 濫打"
3.
y'' + Qy = 0 , 0 < x < L , y(0) = 0 , y'(L) + Ay(L) = 0 , A>0
= =
答案是
an
Q = [ ---- ] , n=1,2,3,..
n L
an
y = Cnsin---x
n L
x
an 為 y=tanx 雨 y = - ---- 焦點橫座標值
AL
我算到
c2(BcosBL + AsinBL)=0
就卡住了..
我知道接下來 是拿 BcosBL + AsinBL 來討論 前提是 我沒做錯@@
4.
Find eigenvalues and eigenfunctions of
y'' + Qy = 0 , y(0) + y'(0) = 0 , y(L) = 0
答案是
an 2
Qn = [ --- ] , n= 1,2,3..
L
an
yn = cn sin ---(x-L)
L
x
an 為 y = --- 雨 y = tanx 焦點橫座標值
L
我也是算到
c2(sinBL - BcosBL) = 0
就接不下去了
=======================================
3.4 兩題 都是在
2
-Q < 0 , 另 -Q = -B , B > 0 的情況下
5.
If 函數 g1 = a0 , g2 = b0 + b1*x
2
g3 = c0 +c1*x + c3*x 在 -1 < x < 1 之區間內行成
= =
單位正教函數集 請求 g1 , g2 , g3 之值..
答案
------- ----- --------
1 | 3 | 5 | 45 2
g1 = ---- , g2 = | ---x , g3 = | --- - | ---x
---- | 2 | 8 | 8
\| 2 \| \| \|
我只知到 我兩個兩個 慢慢積...
積出
3b0*c0 + b0*c3 + b1*c1 = 0
a0*b0 = 0
2a0*c0 + a0*c1 = 0
不知道這些有沒有用處..
請各為高手了@@
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※ 編輯: mdpming 來自: 114.32.91.86 (10/12 21:58)
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