This isn't a homework problem, but it won't let me post on the other page.(adsbygoogle = window.adsbygoogle || []).push({});

A well known vector identity is that rot(rot(E)) = grad(div(E)) - div(grad(E)).

I've actually used this before without encountering any problems, so I don't know if I'm just having a brain fart or something, but shouldn't grad(div(E)) be equal to a vector and div(grad(E)) be equal to a scalar? How can you add or subtract them? It doesn't make any sense.

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# Homework Help: Double curl identity

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