Hey all. Let me just get right to it! Assume you have a function [itex]f:\mathbb{R}^n\rightarrow\mathbb{R}^m[/itex] and we know nothing else except the following equation:(adsbygoogle = window.adsbygoogle || []).push({});

[itex]\triangledown_x\triangledown_x^Tf(x)^TQy=0[/itex]

where [itex]\triangledown_x[/itex] is the gradient with respect to vector [itex]x[/itex] (outer product of two gradient operators is the hessian operator). Also let the dimensions of [itex]Q[/itex] and [itex]y[/itex] conform.

Using the information provided above what can you conclude about [itex]f(x)[/itex] (if anything)? Can you infer that [itex]f(x)[/itex] is linear?

Thank you : )

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# A Hessian of f(x)^T*Q*y

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