matlab求解非线性方程命令,matlab求解非线性方程组 - 仿真模拟 - 小木虫 - 学术 科研 互动社区...

错误提示信息是矩阵奇异，

可能初值不太合适

我用自带fsolve解了下

结果不是很好

[/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]