# Neumann boundary problem

I'm writing a solver for a differential equation with two neumann boundaries (u'(0)=u'(1)=0) and I can't figure out how to determine how to solve the problem. What will my boundaries be and how do I figure this out? The differential equation is $$u''(x)+Ku(x)=0.$$

• Your question is too vague. What do you mean by "What will my boundaries be"? What numerical method do you intend to use? – Wolfgang Bangerth Nov 26 '14 at 13:52
• If your both boundaries have nuemann boundary conditions, then you can only get the information about the gradient of the solution quantity. To get the solution, I think you may have to remove the nullspace from matrix and RHS. – Pranav Dec 26 '14 at 15:35

$\frac{u(i+1)-u(i)}{dx}=0$