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What is the necessary condition for a real symmetric matrix $ A_{m\times m} $ to be written as $B*B^T$ where $B$ is an $(m\times 1)$ matrix ?

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    $B*B^T$ will have rank 12012-06-01
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    then it is not possible unless $A$ has only one independent row/column. Thanks!2012-06-01
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    Consider answering your own question and accepting it.2012-06-01
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    Also relevant to see: The matrix will be semi-positive definite. Also, the numbers on the diagonal have to have squareroots.2012-06-01
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    How about the more general case $A=B*C$ where $C$ is a $1\times m$ matrix and $A$ is a general matrix ?2012-06-02

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