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sunjiahuan銅蟲 (小有名氣)
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[求助]
matlab求解非線性方程組 已有1人參與
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I1=(1.3403/0.323)*(354.3091/443.6719-lambertw((1.0885e-004/443.6719)*exp((330.7*x1+354.3091)/443.6719)))-x1/(0.323+330.7)+1.019*10^(-6)*(exp(x1/1.3403)-1); I2=(1.3403/0.323)*(349.7334/437.9477-lambertw((1.0744e-004/437.9477)*exp((326.4292*x2+349.7334)/437.9477)))-x2/(0.323+326.4292)+1.019*10^(-6)*(exp(x2/1.3403)-1); I3=(1.3403/0.323)*(337.973/423.2354-lambertw((1.0383e-004/423.2354)*exp((315.4524*x3+337.973)/423.2354)))-x3/(0.323+315.4524)+1.019*10^(-6)*(exp(x3/1.3403)-1); I4=(1.3403/0.323)*(324.4644/406.3363-lambertw((9.9677e-005/406.3363)*exp((302.844*x4+324.4644)/406.3363)))-x4/(0.323+302.844)+1.019*10^(-6)*(exp(x4/1.3403)-1); I5=1.019*10^(-6)*(exp(x5/1.3403)-1); 上面是5個方程,I1=f(x1),I2=f(x2),I3=f(x3),I4=f(x4),I5=f(x5); 關(guān)于方程里的lambertw函數(shù),可以在附件(太陽電池I-V方程顯示求解原理研究及應(yīng)用中的第二章中找到)。 而要求解的方程組是由它們5個組成的,如下: x1+x2+x3+x4+x5-30=0 I1-I2=0; I1-I3=0; I1-I4=0; I1-I5=0; 上面的方程組已經(jīng)寫好,在fun.m里。 而在dfun.m 中是方程組里的每一個方程分別對x1,x2 x3 x4 x5 求一階導(dǎo)數(shù)。其實(shí)就是求方程組的雅克比矩陣; 在newton.m里是求解的編程,是我在這個網(wǎng)上(http://hi.baidu.com/aillieo/blog ... c9a59647106493.html)找到的,只是把里面的方程及相關(guān)部分改了一下。 我在matlab里輸入newton([0.01 0.01 0.01 0.01 0.01],0.00001,200) 最后得到的結(jié)果是 In newton at 6 Warning: Matrix is singular, close to singular or badly scaled. Results may be inaccurate. RCOND = NaN. > In newton at 6 ans = NaN NaN NaN NaN NaN。 這種方法是好多學(xué)者用過的,得到的結(jié)果都挺好。所以方法應(yīng)該沒問題。因為我的matlab只學(xué)了個皮毛,不知道這里面哪出錯了,還請各位高手給指點(diǎn)一下。 |
材料+新能源+催化+外語 |
鐵桿木蟲 (職業(yè)作家)
榮譽(yù)版主 (著名寫手)
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錯誤提示信息是矩陣奇異, 可能初值不太合適 我用自帶fsolve解了下 結(jié)果不是很好 [/code] function aa [X,FVAL,EXITFLAG,OUTPUT] =fsolve(@fun,[18.7783 0.01 18.1315 18.0062 -2],optimset('MaxFunEvals',1000)) function f=fun(x) x1=x(1); x2=x(2); x3=x(3); x4=x(4); x5=x(5); f1=x1+x2+x3+x4+x5-30; f2=4.1495*(0.7986-lambertw(2.4534e-007*exp((330.7*x1+354.3091)/443.6719)))-x1/331.0230+1.019e-6*(exp(x1/1.3403)-1)-4.1495*(0.7986-lambertw(2.4533e-007*exp((326.4292*x2+349.7334)/437.9477)))+x2/(0.323+326.4292)-1.019*10^(-6)*(exp(x2/1.3403)-1); f3=4.1495*(0.7986-lambertw(2.4534e-007*exp((330.7*x1+354.3091)/443.6719)))-x1/331.0230+1.019e-6*(exp(x1/1.3403)-1)-4.1495*(0.7985-lambertw(2.4532e-007*exp((315.4524*x3+337.973)/423.2354)))+x3/(0.323+315.4524)-1.019*10^(-6)*(exp(x3/1.3403)-1); f4=4.1495*(0.7986-lambertw(2.4534e-007*exp((330.7*x1+354.3091)/443.6719)))-x1/331.0230+1.019e-6*(exp(x1/1.3403)-1)-4.1495*(0.7985-lambertw( 2.4531e-007*exp((302.844*x4+324.4644)/406.3363)))+x4/(0.323+302.844)-1.019*10^(-6)*(exp(x4/1.3403)-1); f5=4.1495*(0.7986-lambertw(2.4534e-007*exp((330.7*x1+354.3091)/443.6719)))-x1/331.0230+1.019e-6*(exp(x1/1.3403)-1)-1.019*10^(-6)*(exp(x5/1.3403)-1); f=[f1 f2 f3 f4 f5]; [/code] Solver stopped prematurely. fsolve stopped because it exceeded the function evaluation limit, options.MaxFunEvals = 1000 (the selected value). X = 18.7895 19.0894 19.0963 19.1094 -46.0868 FVAL = -0.0022 -0.0180 -0.0172 -0.0175 2.7252 EXITFLAG = 0 OUTPUT = iterations: 180 funcCount: 1001 algorithm: 'trust-region dogleg' firstorderopt: 0.0022 message: [1x143 char] |

銅蟲 (小有名氣)
銅蟲 (小有名氣)
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