Question

怎样用matlab接下面的多元二次方程组 或用其他工具也行

7*n1^2+290*n7-3*n7^2=5887
7*n2^2-10*n1*n2+3*n1^2+290*n7-3*n7^2=5887
7*n3^2-10*n2*n3+3*n2^2+290*n7-3*n7^2=5887
7*n4^2-10*n3*n4+3*n3^2+290*n7-3*n7^2=5887
7*n5^2-10*n4*n5+3*n4^2+290*n7-3*n7^2=5887
7*n6^2-10*n5*n6+3*n5^2+290*n7-3*n7^2=5887
4*n7^2-10*n6*n7+3*n6^2+290*n7=5887

Answer 1

建立.m文件
function F=myfun(x)
n1=x(1);
n2=x(2);
n3=x(3);
n4=x(4);
n5=x(5);
n6=x(6);
n7=x(7);
f1=7*n1^2+290*n7-3*n7^2-5887;
f2=7*n2^2-10*n1*n2+3*n1^2+290*n7-3*n7^2-5887;
f3=7*n3^2-10*n2*n3+3*n2^2+290*n7-3*n7^2-5887;
f4=7*n4^2-10*n3*n4+3*n3^2+290*n7-3*n7^2-5887;
f5=7*n5^2-10*n4*n5+3*n4^2+290*n7-3*n7^2-5887;
f6=7*n6^2-10*n5*n6+3*n5^2+290*n7-3*n7^2-5887';
f7=4*n7^2-10*n6*n7+3*n6^2+290*n7-5887;
F=[f1,f2,f3,f4,f5,f6,f7]';
---------------
options=optimset('maxfuneval',1000);
[x,fval,exitflag,output]=fsolve(@myfun,[1 1 1 1 1 1 1],options)

Equation solved.

fsolve completed because the vector of function values is near zero
as measured by the default value of the function tolerance, and
the problem appears regular as measured by the gradient.

<stopping criteria details>

x =

6.3729 11.1800 15.1144 18.4942 21.4887 24.1984 26.6875

fval =

1.0e-009 *

0.1055
0.0018
0.0146
-0.0018
0.0036
0.0055
-0.0018

exitflag =

1

output =

iterations: 9
funcCount: 80
algorithm: 'trust-region dogleg'
firstorderopt: 1.6297e-008
message: [1x695 char]

Answer 2

N1 6.372916
N7 26.68746
N2 11.18002
N3 15.11437
N4 18.49419
N5 21.48874
N6 24.19835
lingo得出