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Topic:
why the sigma of symmetrical svd for a real symmetric matrix is negative?
Replies:
4
Last Post:
Dec 27, 2012 7:30 PM



Rick
Posts:
1
Registered:
12/26/12


why the sigma of symmetrical svd for a real symmetric matrix is negative?
Posted:
Dec 26, 2012 9:25 PM


Hi everyone, as we know, for a real symmetric matrix A, A, there exists a singular value decomposition as A=USU', and S should be a rectangular diagonal matrix with nonnegative real numbers on the diagonal. But when I use the command schur(), it seems that S appears negative real numbers on the diagonal as the following. Is there any problem?
Thanks a lots!
>>A= 1.3410 0.5350 0.2995 1.1138 0.5350 2.5191 0.1422 0.4953 0.2995 0.1422 1.4695 0.2981 1.1138 0.4953 0.2981 2.2897
>>[u,s]=schur(A)
u =
0.4768 0.2191 0.0448 0.8501 0.5549 0.8260 0.0177 0.0974 0.1944 0.1630 0.9621 0.1004 0.6534 0.4931 0.2685 0.5078
s =
3.6119 0 0 0 0 2.0534 0 0 0 0 1.3749 0 0 0 0 0.5790



