推 bat205:感恩~ 05/26 10:12
※ 引述《bat205 (時速200km)》之銘言：
: http://eserv.lib.ncku.edu.tw/exam/showfile.php?file=ZXhhbS+606Ror1qm0rjVL6R1vse
: wfC++97HxpHW1e77HqHQvOTC+97HxqdIvpHW1e7zGvscucGRm
: 第3題的b小題
: 答案是c
: 感恩~
[u(t)-u(t-1)]-[u(t-1)-u(t-2)]+[u(t-2)-u(t-3)]-.........
=u(t)-2u(t-1) +2u(t-2)-2u(t-3)+2u(t-4)-.....
L[f(t)]=1/s -2/s*e^-s +2/s*e^-2s -2/s*d^-3s +....
=1/s[1-2e^-s +2e^-2s -2e^-3s +2e^-4s -.....]
=1/s[tanh(s/2)]
補充:coshs=(e^s＋e^-s)/2 , sinhs=(e^s－e^-s)/2
(coshs-1)/sinhs=tanh(s/2)
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