[求助] 怎样将正交变换化为标准型如下题 谢谢
f(x1,x2,x3)=x1^2+x2^2+x3^2+x4^2+2x1x2-2x1x4+2x2x3-2x3x4
A =
1 2 0 -2
2 1 2 0
0 2 1 -2
-2 0 -2 1
?[x,lamda]=eig(A)
x =
0.5774 0.4082 0.5000 -0.5000
0.4082 -0.5774 0.5000 0.5000
-0.5774 -0.4082 0.5000 -0.5000
0.4082 -0.5774 -0.5000 -0.5000
x为换基矩阵，将系数矩阵转换为对角阵
