Question

求matlab代码，知道x1^i+x2^i+x3^i+x4^i=i(i=1,2,3,4)计算x1*x2*x3*x4

matlab的代码

Answer 1

可以用solve()函数求解。

代码如下：

[x1,x2,x3,x4]=solve('x1+x2+x3+x4=1','x1^2+x2^2+x3^2+x4^2=2','x1^3+x2^3+x3^3+x4^3=3','x1^4+x2^4+x3^4+x4^4=4');

 x1.*x2.*x3.*x4

计算结果

x1.*x2.*x3.*x4=0.041666666666666666666666666666667

Answer 2

>> syms x1 x2 x3 x4
[x1,x2,x3,x4]=solve(x1+x2+x3+x4==1,x1^2+x2^2+x3^2+x4^2==2,x1^3+x2^3+x3^3+x4^3==3,x1^4+x2^4+x3^4+x4^4==4,'x1','x2','x3','x4')

x1 =

- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
0.15677269151057856713696995940447 - 5.2744707027884514456191888597788e-34*i
0.15677269151057856713696995940447 - 5.2126621996317578305468655320187e-34*i
0.15677269151057856713696995940447 + 3.6734198463196484624023016788195e-40*i
1.4201621170697498052123450313422 - 4.5917748078995605780028770985244e-41*i
1.4201621170697498052123450313422 + 5.2716169147453418687199600716621e-35*i
1.4201621170697498052123450313422 + 5.2098506559168809296049543703713e-35*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
0.15677269151057856713696995940447 - 5.2744709323771918405972177599227e-34*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
0.15677269151057856713696995940447 - 5.2126651842853829652612412338888e-34*i
0.15677269151057856713696995940447 - 3.6734198463196484624023016788195e-40*i
1.4201621170697498052123450313422 + 4.5917748078995605780028770985244e-41*i
1.4201621170697498052123450313422 + 5.2716238024075537180608270759777e-35*i
1.4201621170697498052123450313422 + 5.2098437682546690802640873660556e-35*i

x2 =

- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
0.15677269151057856713696995940447 - 5.2744707027884514456191888597788e-34*i
0.15677269151057856713696995940447 - 5.2126621996317578305468655320187e-34*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
0.15677269151057856713696995940447 - 5.2744709323771918405972177599227e-34*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
0.15677269151057856713696995940447 + 3.6734198463196484624023016788195e-40*i
1.4201621170697498052123450313422 - 4.5917748078995605780028770985244e-41*i
1.4201621170697498052123450313422 + 5.2716169147453418687199600716621e-35*i
1.4201621170697498052123450313422 + 5.2098506559168809296049543703713e-35*i
0.15677269151057856713696995940447 - 3.6734198463196484624023016788195e-40*i
1.4201621170697498052123450313422 + 4.5917748078995605780028770985244e-41*i
1.4201621170697498052123450313422 + 5.2716238024075537180608270759777e-35*i
1.4201621170697498052123450313422 + 5.2098437682546690802640873660556e-35*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
0.15677269151057856713696995940447 - 5.2126651842853829652612412338888e-34*i

x3 =

0.15677269151057856713696995940447
1.4201621170697498052123450313422
1.4201621170697498052123450313422 + 5.2716192106327458185002490731006e-35*i
1.4201621170697498052123450313422 + 5.2098483600294769798246653689327e-35*i
0.15677269151057856713696995940447
1.4201621170697498052123450313422
1.4201621170697498052123450313422 + 5.2716192106327458185002490731006e-35*i
1.4201621170697498052123450313422 + 5.2098483600294769798246653689327e-35*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
0.15677269151057856713696995940447 - 5.2126654138741233602392701340327e-34*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
0.15677269151057856713696995940447 - 5.2126654138741233602392701340327e-34*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
0.15677269151057856713696995940447 - 5.2744707027884514456191888597788e-34*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
0.15677269151057856713696995940447 - 5.2744707027884514456191888597788e-34*i
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i

x4 =

1.4201621170697498052123450313422
0.15677269151057856713696995940447
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
1.4201621170697498052123450313422
0.15677269151057856713696995940447
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
1.4201621170697498052123450313422
0.15677269151057856713696995940447
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
1.4201621170697498052123450313422
0.15677269151057856713696995940447
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
1.4201621170697498052123450313422
0.15677269151057856713696995940447
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i
1.4201621170697498052123450313422
0.15677269151057856713696995940447
- 0.28846740429016418617465749537331 + 0.3223856403744705053915950268905*i
- 0.28846740429016418617465749537331 - 0.3223856403744705053915950268905*i