# Posts by DrPhysics

Total # Posts: 2

**Quantum mechanics, eigenfunctions!**

You are absolutely right. To be an eigenfunction, the operator has to reproduce the function with some multiplicative constant. Even without doing a lot of work, you can see for the special case of a=0 it doesn't work because you need to take four derivatives of sine to ...

**(expi)^i**

This question is not well defined. By 'expi' do you mean exp(i)? In other words, is the expression [exp(i)]^i ? If so, then the answer is undoubtedly exp(-1). You can use Euler's equation to show this, but it is much easier to use this fact about exponents: (a^b)^c...