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xhw2211金蟲 (正式寫手)
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[求助]
mathematica 編程求助
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頭一次用mathtematica編的程序,總是沒有畫出圖形,不知道錯在什么地方了,大?匆幌。 z1 = LaplaceTransform[Exp[-10*t - 5*t^2], t, s]; z2 = LaplaceTransform[(10 + 10*t)*Exp[-10*t - 5*t^2], t, s]; z3 = Simplify[z2]; equ1 = z1 + z3*y - z; y1 = LaplaceTransform[7*Exp[-7*t], t, s]; y2 = LaplaceTransform[110*Exp[-110*t], t, s]; equ2 = y1*x + y2*z - y; x1 = LaplaceTransform[120*Exp[-120*t], t, s]; equ3 = x1*y - x; Solve[{equ1 == 0, equ2 == 0, equ3 == 0}, {x, y, z}] m = InverseLaplaceTransform[z, s, t] Plot[z, {t, 0, 1}, PlotStyle -> {Red, Thickness[0.008]}] |
版主 (知名作家)

金蟲 (正式寫手)
金蟲 (正式寫手)
至尊木蟲 (正式寫手)
金蟲 (正式寫手)
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我按你的方法改了程序,但是還是沒有結(jié)果,感覺是不是拉普拉斯變換后解出的Z表達式太復(fù)雜,mathematica無法進行拉普拉斯反變換???下面是程序運行后得到的m m={1/2 Sqrt[\[Pi]/5] InverseLaplaceTransform[( E^(5 + s + s^2/20) (1 - 840/((7 + s) (120 + s))) Erfc[(10 + s)/( 2 Sqrt[5])])/( 1 - 840/((7 + s) (120 + s)) - ( 110 (1 - 1/2 E^(1/20 (10 + s)^2) Sqrt[\[Pi]/5] s Erfc[(10 + s)/(2 Sqrt[5])]))/(110 + s)), s, t]} |
金蟲 (正式寫手)
金蟲 (正式寫手)
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把修改后的程序貼出來: z1 = LaplaceTransform[Exp[-10*t - 5*t^2], t, s]; z2 = LaplaceTransform[(10 + 10*t)*Exp[-10*t - 5*t^2], t, s]; z3 = Simplify[z2]; equ1 = z1 + z3*y - z; y1 = LaplaceTransform[7*Exp[-7*t], t, s]; y2 = LaplaceTransform[110*Exp[-110*t], t, s]; equ2 = y1*x + y2*z - y; x1 = LaplaceTransform[120*Exp[-120*t], t, s]; equ3 = x1*y - x; rr = Solve[{equ1 == 0, equ2 == 0, equ3 == 0}, {x, y, z}]; z = z /. rr; m = InverseLaplaceTransform[z, s, t] Plot[z, {t, 0, 1}, PlotStyle -> {Red, Thickness[0.008]}] |
金蟲 (正式寫手)
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下面這個是對的: z1 = LaplaceTransform[Exp[-10*t - 5*t^2], t, s]; z2 = LaplaceTransform[(10 + 10*t)*Exp[-10*t - 5*t^2], t, s]; z3 = Simplify[z2]; equ1 = z1 + z3*y - z; y1 = LaplaceTransform[7*Exp[-7*t], t, s]; y2 = LaplaceTransform[110*Exp[-110*t], t, s]; equ2 = y1*x + y2*z - y; x1 = LaplaceTransform[120*Exp[-120*t], t, s]; equ3 = x1*y - x; rr = Solve[{equ1 == 0, equ2 == 0, equ3 == 0}, {x, y, z}]; z = z /. rr; m = InverseLaplaceTransform[z, s, t] Plot[m, {t, 0, 1}, PlotStyle -> {Red, Thickness[0.008]}] |
金蟲 (正式寫手)
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