1. The problem statement, all variables and given/known data the integral table says when you have the above form this will be the answer: 2. Relevant equations 3. The attempt at a solution I looked at the integral table here http://integral-table.com/integral-table.html#SECTION00006000000000000000 and it says erf - I don't know what that means. In any case the erf x√a does not appear in the answer. I also don't understand the step A√(λ/π) = A = √λ/π I also don't see why there is no two in the denominator.