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yatlan

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[交流] 【求助】matlab 求解方程组时出错,非常急,好心人帮忙!

clear;
syms  a b c d e cl cz ll lz cll lll czl lzl;
a=ll*lz*cl*cz;
b=ll*cl+lz*cz+lz*cl;
c=ll*lz*cl;
d=lz;
e=(b+(b^2-4*a)^(1/2))/2;
cll=(a*(a-e^2))/(e*(a*d-c*e))-3.071;
lll=(a*d-c*e)/(a-e^2)-7.533;
czl=(a-e^2)/(c-d*e)-1.313;
lzl=(e*(c-d*e))/(a-e^2)-3.222;
solve(cll,lll,czl,lzl);

如上的程序在最后solve 求解时提示
??? Error using ==> subsref
Index exceeds matrix dimensions.

Error in ==> sym.subsref at 16
  y = builtin('subsref',struct(x),a);

Error in ==> solve at 191
   S.(char(symvars(j))) = R(:,j);

再线等................!
非常感谢

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1楼 2009-10-02 01:14:43

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eaglefy

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yatlan(金币+3,VIP+0):非常感谢您的帮忙！！！3个金币的小礼物 10-3 21:07

好像是无解，仔细检查一下方程

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7楼2009-10-03 10:01:20

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bote

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sorry for some confusiion?

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小木虫(金币+0.5):给个红包，谢谢回帖交流
sunxiao(金币+2,VIP+0):thank you for your suggestions 10-3 00:13

1. seems using solve(cll,lll,czl,lzl, 'cz', 'cl', 'lz', 'll')

have tried a simple case like what you are going to do. it works.
the code is as follows:

clear;
clc;
syms a u v;
l=a*u^2 + v^2;
m=u-v-1;
n=a^2-5*a+6;
A=solve(l,m,n, 'a','u','v');

therefore, it seems that your equations are too complicated for the matlab. maybe, the other approaches had to be considered, such as simplify your equations first.
anyway, show it up here if you solve the problem. good luck.

again: if you remove only one denominator from any one of your four equations, the code can run through to the end after replacing the solve function with the one given above. so, you had to simplify your equations first.

[ Last edited by bote on 2009-10-2 at 12:27 ]

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2楼2009-10-02 06:28:38

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