为什么线性方程组解不出答案。

>> Xa1=1;

Xa2=1;

Xa3=1;

Ya1=2;

Ya2=3;

Ya3=5;

Za1=3;

Za2=4;

Za3=7;

Xb1=3;

Xb2=3;

Xb3=3;

Yb1=8;

Yb2=7;

Yb3=9;

Zb1=10;

Zb2=12;

Zb3=14;

syms T1 T2 T3 Wx Wy Wz M;

P1=Xa1-Xb1+T1-Wy*Za1+Wz*Ya1+Xa1*M;

P2=Ya1-Yb1+T2+Wx*Za1-Wz*Xa1+Ya1*M;

P3=Za1-Zb1+T3-Wx*Ya1+Wy*Xa1+Za1*M;

P4=Xa2-Xb2+T1-Wy*Za2+Wz*Ya2+Xa2*M;

P5=Ya2-Yb2+T2+Wx*Za2-Wz*Xa2+Ya2*M;

P6=Za2-Zb2+T3-Wx*Ya2+Wy*Xa2+Za2*M;

P7=Xa3-Xb3+T1-Wy*Za3+Wz*Ya3+Xa3*M;

P8=Ya3-Yb3+T2+Wx*Za3-Wz*Xa3+Ya3*M;

P9=Za3-Zb3+T3-Wx*Ya3+Wy*Xa3+Za3*M;

[T1,T2,T3,Wx,Wy,Wz,M]=solve('Xa1-Xb1+T1-Wy*Za1+Wz*Ya1+Xa1*M','Ya1-Yb1+T2+Wx*Za1-Wz*Xa1+Ya1*M','Za1-Zb1+T3-Wx*Ya1+Wy*Xa1+Za1*M','Xa2-Xb2+T1-Wy*Za2+Wz*Ya2+Xa2*M','Ya2-Yb2+T2+Wx*Za2-Wz*Xa2+Ya2*M','Za2-Zb2+T3-Wx*Ya2+Wy*Xa2+Za2*M','Xa3-Xb3+T1-Wy*Za3+Wz*Ya3+Xa3*M','Ya3-Yb3+T2+Wx*Za3-Wz*Xa3+Ya3*M','Za3-Zb3+T3-Wx*Ya3+Wy*Xa3+Za3*M',T1,T2,T3,Wx,Wy,Wz,M);

以上是代码

Warning: 9 equations in 7 variables.

> In D:\matlab\R2013a\toolbox\symbolic\symbolic\symengine.p>symengine at 56

In mupadengine.mupadengine>mupadengine.evalin at 97

In mupadengine.mupadengine>mupadengine.feval at 150

In solve at 170

Warning: Explicit solution could not be found.

> In solve at 179

以上是错误警告

为什么解出来是空值，或者是[]

按道理说九个等式 七个未知量可以的啊

Answer 1

[dedan]

数值解Matlab的话用fsolve。

另外用1stOpt更简单：

Constant Xa1=1, Xa2=1, Xa3=1, Ya1=2, Ya2=3, Ya3=5, Za1=3, Za2=4, Za3=7,
         Xb1=3, Xb2=3, Xb3=3, Yb1=8, Yb2=7, Yb3=9, Zb1=10, Zb2=12, Zb3=14;
Function
Xa1-Xb1+T1-Wy*Za1+Wz*Ya1+Xa1*M;
Ya1-Yb1+T2+Wx*Za1-Wz*Xa1+Ya1*M;
Za1-Zb1+T3-Wx*Ya1+Wy*Xa1+Za1*M;
Xa2-Xb2+T1-Wy*Za2+Wz*Ya2+Xa2*M;
Ya2-Yb2+T2+Wx*Za2-Wz*Xa2+Ya2*M;
Za2-Zb2+T3-Wx*Ya2+Wy*Xa2+Za2*M;
Xa3-Xb3+T1-Wy*Za3+Wz*Ya3+Xa3*M;
Ya3-Yb3+T2+Wx*Za3-Wz*Xa3+Ya3*M;
Za3-Zb3+T3-Wx*Ya3+Wy*Xa3+Za3*M;

没有精确实数解，近似解：

t1: 2.24999998713377

wy: -5.59293952314284E-8

wz: -7.39378106406253E-8

m: -0.250000000750601

t2: 6.54999992665872

wx: -0.225000000443284

t3: 7.75000005560102