Nick

Hmm... I bet that's it. Thanks.

Okay, thanks that makes sense. Then where was I getting that linear combinations of solutions to Schrodinger's equation are also solutions? Am I just misremembering something...

I have a quick QM question that I should really know the answer to -- having a brain fart here. Any linear combination of solutions to HΨ = EΨ is also a solution, correct? So any linear combination of energy eigenstates is also a solution. So assume you put the Hilbert space in a basis of the orthonormal energy eigenstates. Now any function can be represented as a linear combination of basis functions, right? But not every function is a solution to HΨ = EΨ. So where am I messing up here?

@Expert, thanks

@Expert, are you there?

I thought dot product was only defined between two vectors.

But then what does it mean to do a dot product with a matrix?

So, I guess direct multiplication of two vectors (length 3) results in a 3x3 matrix.

Where ∇ and u are vectors, p is a scalar, and * is the dot product

Let me retry that: ∇ *(puu)

Hmm.

@Expert, so I have an expression $\vec{\nabla}\cdot(\rho \vec{u} \vec{u}$

Wait, so the expert isn't a bot? Crap, I had a strange conversation earlier then...

Is there someone on here who wouldn't mind helping me with tensor multiplication?

Thank you for the help!

I just modified the question

Yes, that's correct.

Alright. And I suppose my last bullet-point was kind of general, but would you happen to know the answer to that off-hand? You seem to know this place fairly well so I imagine you have insight into it.

My second-to-last bullet point is very specific (so I imagine it has not been asked on here), and it is also probably the most important one.

Can do that too.

Okay, I can see that. I will do so.

Hi, yes I posted that question.