Why does ?

Printable View

- June 22nd 2010, 09:59 AMmathman88Simple question
Why does ?

- June 22nd 2010, 10:16 AMAckbeet
Integrate both sides. What do you get?

- June 22nd 2010, 11:59 AMmathman88
I understand that, but does that imply that's the unique solution?

- June 22nd 2010, 12:01 PMAckbeet
Well, you have an infinite family of solutions depending on your initial condition. However, the fact that the RHS of your DE, namely 0, is Lipschitz and continuous, is enough to guarantee the uniqueness of the solution to an initial value problem (an initial value problem is your original DE plus an initial condition to determine the constant of integration). Does that make sense?

- June 22nd 2010, 12:23 PMmathman88
Why does Lipschitz continuity guarantee uniqueness of the solution (up to a constant)?

- June 22nd 2010, 12:31 PMAckbeet
Because of the Picard-Lindelof theorem. If you're curious, by all means investigate the proof of that theorem.

- June 26th 2010, 02:59 PMHallsofIvy