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Math Help - Norm inequality

  1. #1
    Member Mollier's Avatar
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    Norm inequality

    Hi,

    I need to show that \| |A| \|_2 \leq \sqrt{n} \|A\|_2 where A is m\times n. THe |A| notation means we take the absolute value of all elements of A.

    I've tried a few things (with no luck), such that first trying to show that \|A\|_{\infty}\geq \| |A| \|_2,
    and then use the fact that \sqrt{n}\|A\|_2\geq \|A\|_{\infty}.

    Would be great if someone could give me a hint or two.

    Thanks.
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  2. #2
    Super Member girdav's Avatar
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    Re: Norm inequality

    I don't know what the norm notations refer, but did you try to use Cauchy-Schwarz inequality?
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