5楼: Originally posted by kweewu at 2015-08-11 16:03:34
谢谢！那如此在您的代码上要怎样使x，y，z都是正数呢？...

function solve_eq
clear all;clc
format long
global a b c cos1 cos2 cos3

cos1=0.37461;
cos2=0.24192;
cos3=0.17365;

a=7.2;
b=14.2;
c=18.1;


x0=[-1 0 0];

options=optimset('TolFun',1e-9);
[x fval]=fsolve(@fun,x0,options);
[x;fval]'
x'


function f=fun(u)

global a b c cos1 cos2 cos3

x=u(1);
y=u(2);
z=u(3);

f(1)=x^2+y^2-2*x*y*cos1-a^2;
f(3)=y^2+z^2-2*y*z*cos2-b^2;
f(2)=z^2+x^2-2*z*x*cos3-c^2;

2楼: Originally posted by 月只蓝 at 2015-08-11 13:09:22
不存在满足f=0的解。

使得f尽量小的解：
   8.063894135668461
   0.049339384803544
-14.560697883414663

或者：
  -8.063894144363893
  -0.049339340193223
  14.560697881727988

MATLAB代码：
...

3楼: Originally posted by kweewu at 2015-08-11 15:46:12
您好！忘了说了，x，y，z均是正数，这样怎样相应的修改一下代码呢？...