→ Secertman:嗯嗯 這樣比較快 04/10 09:36
推 Aaron1025:跟我一樣算法 前面推文有講~ 04/10 11:29
※ 引述《Secertman (獨在異鄉為異客)》之銘言：
: ※ 引述《ICRO (聖文大色胚)》之銘言：
: : y"+9y=tcost
個人覺得 用逆運子還是最快...
( D^2 + 9 )y = tcost
yh = c1 * cos3t + c2 * sin3t
1 it it 1
yp = Re ---------- te = Re[ e ----------- t ]
D^2 + 9 (D+i)^2 + 9
it 1 it 1 1
= Re [ e -------------- t ] = Re [ e * --- * ----------------------- t ]
D^2 +2iD + 8 8 1- (-iD/4 - D^2 / 8 )
it 1 i
= Re [ e * ------ * ( t - ----- ) ]
8 4
= Re [ ( cost + isint ) * ( t - i/4 ) * 1/8 ]
tcost sint
= ----- + ------
8 32
=> y = yh + yp
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 140.114.198.110