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A general way to get a matrix norm is inducing it from a vector norm.

The question is, can the Hilbert-Schmidt norm obtained this way?

As a norm general question, is every matrix norm obtained this way?

The crucial condition is $\|XY\| \leq \|X\|\,\|Y\|$.

egreg
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John
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1 Answers1

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The Hilbert Schmidt norm cannot be obtained as an induced norm. Of the Schatten-$p$ norms, only the $\infty$ norm (which is also the induced $2$-norm) is an induced norm.

A quick way to see that the Hilbert Schmidt norm is not induced by any matrix norm is to note that the identity matrix $I$ satisfies $\|I\| > 1$.

Ben Grossmann
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