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qjf880726捐助貴賓 (正式寫手)
煤炭機械
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[求助]
matlab新手求助一下關于解決一次方程解析解的問題
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方程如下: y=solve('y^3-5*k/m*y^2+6*k^2/m^2*y-k^3/m^3') 得到的答案為: y = [ (1/6*(28+84*i*3^(1/2))^(1/3)+14/3/(28+84*i*3^(1/2))^(1/3)+5/3)*k/m] [ (-1/12*(28+84*i*3^(1/2))^(1/3)-7/3/(28+84*i*3^(1/2))^(1/3)+5/3+1/2*i*3^(1/2)*(1/6*(28+84*i*3^(1/2))^(1/3)-14/3/(28+84*i*3^(1/2))^(1/3)))*k/m] [ (-1/12*(28+84*i*3^(1/2))^(1/3)-7/3/(28+84*i*3^(1/2))^(1/3)+5/3-1/2*i*3^(1/2)*(1/6*(28+84*i*3^(1/2))^(1/3)-14/3/(28+84*i*3^(1/2))^(1/3)))*k/m] >> 這個是書上的方程,書上給出的解沒有復數(shù)i,不知道為什么用matlab6求解后得到了復數(shù)i了呢??真心求幫組,我的幣不多 見諒 |

捐助貴賓 (正式寫手)
煤炭機械
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呵呵 謝謝 我的問題解決了 原來我把我心愛的matlab6.5換成論壇里提供下載的matlab2012后再輸入就正常了 很神奇 我是各種無語。。。 >> y=solve('y^3-5*k/m*y^2+6*k^2/m^2*y-k^3/m^3') y = ((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3) + (5*k)/(3*m) + (7*k^2)/(9*m^2*((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)) (5*k)/(3*m) + (3^(1/2)*(((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3) - (7*k^2)/(9*m^2*((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)))*i)/2 - ((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)/2 - (7*k^2)/(18*m^2*((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)) (5*k)/(3*m) - (3^(1/2)*(((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3) - (7*k^2)/(9*m^2*((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)))*i)/2 - ((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)/2 - (7*k^2)/(18*m^2*((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)) >> |

榮譽版主 (著名寫手)
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專家經(jīng)驗: +4 |
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y=solve('y^3-5*k/m*y^2+6*k^2/m^2*y-k^3/m^3','y') y = ((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3) + (5*k)/(3*m) + (7*k^2)/(9*m^2*((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)) (5*k)/(3*m) - ((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)/2 - (7*k^2)/(18*m^2*((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)) - (3^(1/2)*(((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3) - (7*k^2)/(9*m^2*((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)))*i)/2 (5*k)/(3*m) - ((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)/2 - (7*k^2)/(18*m^2*((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)) + (3^(1/2)*(((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3) - (7*k^2)/(9*m^2*((-(49*k^6)/(108*m^6))^(1/2) + (7*k^3)/(54*m^3))^(1/3)))*i)/2 |

榮譽版主 (著名寫手)
![]() |
專家經(jīng)驗: +4 |

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