※ 引述《MuseLand (I will survive)》之銘言： : %以下是有的數值 : packet1=300; : packet2=300; : packet3=300; : Rsr1=30; : Rsr2=30; : Rr1d1=10; : Rr1d2=10; : Rr1d3=10; : Rr2d1=10; : Rr2d2=10; : Rr2d3=10; : Rsd1=30; : Rsd2=30; : Rsd3=30; : %想利用下列等式求解Xr1d1 Xr1d2 Xr1d3 Xr2d1 Xr2d2 Xr2d3 : eq1 = 'Rsr1=Xr1d1+Xr1d2+Xr1d3'; : eq2 = 'Rsr2=Xr2d1+Xr2d2+Xr2d3'; : eq3 = 'Vr1d1=Xr1d1*Rr1d1/(Xr1d1+Rr1d1)'; : eq4 = 'Vr2d1=Xr2d1*Rr2d1/(Xr2d1+Rr2d1)'; : eq5 = 'Vr1d2=Xr1d2*Rr1d2/(Xr1d2+Rr1d2)'; : eq6 = 'Vr2d2=Xr2d2*Rr2d2/(Xr2d2+Rr2d2)'; : eq7 = 'Vr1d3=Xr1d3*Rr1d3/(Xr1d3+Rr1d3)'; : eq8 = 'Vr2d3=Xr2d3*Rr2d3/(Xr2d3+Rr2d3)'; : eq9 = 'packet1/(Rsd1+Vr1d1+Vr2d1)=packet2/(Rsd2+Vr1d2+Vr2d2)'; : eq10 = 'packet2/(Rsd2+Vr1d2+Vr2d2)=packet3/(Rsd3+Vr1d3+Vr2d3)'; : eq11 = 'packet1/(Rsd1+Vr1d1+Vr2d1)=packet3/(Rsd3+Vr1d3+Vr2d3)'; : [Xr1d1 Xr1d2 Xr1d3 Xr2d1 Xr2d2 Xr2d3 ] = solve( : eq1,eq2,eq3,eq4,eq5,eq6,eq7,eq8,eq9,eq10,eq11 ) : 程式碼如上面 : 抱歉剛接觸matlab : 原本想測試看看所以故意湊好解的數字 : 想說至少會有[10 10 10 10 10 10]這個解 : 可是卻只出現[ empty sym ]以及[] : 請問是什麼原因 : 請板上的先進幫忙解惑一下 thanks 我直接用eq1~eq11 matlab解不出來 不過把eq3~eq8代到eq9~eq11就可以解 packet1=300; packet2=300; packet3=300; Rsr1=30; Rsr2=30; Rr1d1=10; Rr1d2=10; Rr1d3=10; Rr2d1=10; Rr2d2=10; Rr2d3=10; Rsd1=30; Rsd2=30; Rsd3=30; syms Xr1d1 Xr1d2 Xr1d3 Xr2d1 Xr2d2 Xr2d3 Vr1d1 Vr1d2 Vr1d3 Vr2d1 Vr2d2 Vr2d3 eq1 = -Rsr1+Xr1d1+Xr1d2+Xr1d3; eq2 = -Rsr2+Xr2d1+Xr2d2+Xr2d3; eq9 = -packet1/(Rsd1+Xr1d1*Rr1d1/(Xr1d1+Rr1d1)+Xr2d1*Rr2d1/(Xr2d1+Rr2d1))+... packet2/(Rsd2+Xr1d2*Rr1d2/(Xr1d2+Rr1d2)+Xr2d2*Rr2d2/(Xr2d2+Rr2d2)); eq10 = -packet2/(Rsd2+Xr1d2*Rr1d2/(Xr1d2+Rr1d2)+Xr2d2*Rr2d2/(Xr2d2+Rr2d2))+... packet3/(Rsd3+Xr1d3*Rr1d3/(Xr1d3+Rr1d3)+Xr2d3*Rr2d3/(Xr2d3+Rr2d3)); eq11 = -packet1/(Rsd1+Xr1d1*Rr1d1/(Xr1d1+Rr1d1)+Xr2d1*Rr2d1/(Xr2d1+Rr2d1))+... packet3/(Rsd3+Xr1d3*Rr1d3/(Xr1d3+Rr1d3)+Xr2d3*Rr2d3/(Xr2d3+Rr2d3)); [Xr1d1 Xr1d2 Xr1d3 Xr2d1 Xr2d2 Xr2d3 ] = solve... (eq1,eq2,eq9,eq10,eq11,'Xr1d1','Xr1d2','Xr1d3' ,'Xr2d1','Xr2d2','Xr2d3') 因為只有5條方程式解6個未知數 它會顯示警告 然後出來的解都是參數解 不知道是不是你要的 --

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