matrix expression simplify [closed]
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开发者_开发知识库Closed 11 years ago.
Improve this questioni am wondering if it is possible to simplify:
T*V + V*T // V = V^(t) symmetric
where both operands are matrixes
I don't think this is possible due to the following considerations:
If we multiply two matrices A
and T
, where A
is symmetric (i.e. A(i,j) = A(j,i)
), we have the following:
For A*T
we have that the item in row z
and column s
is computed as:
__n__
\
/ A(z,i)*T(i,s)
-----
i=1
For the other way around, T*A
, we get for row z
, column s
:
__n__ __n__
\ \
/ T(z,i)*A(i,s) = / T(z,i)*A(s,i)
----- -----
i=1 i=1
So, as long as we do not know anything about the entries T(i,j)
in T
, I think we can not say how these sums relate to each other.
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