Ramanujan summation

Ramanujan summation is a technique discovered by Srinivasa Ramanujan for assigning a sum to divergent series; it involves an application of the Euler-Maclaurin summation formula to the Riemann zeta function and gives summations such as:

<math>1+2+3+\cdots = -\frac{1}{12}</math>

This technique has been used to renormalize the force due to Casimir Effect using Zeta function regularization.