Thread: calculation 4.8 on p.139 View Single Post
#6
08-11-2013, 11:14 AM
The first step of the Calculation 4.8 on p.139 is still not sinking into my brain somehow. It feels like in the first step we pulled out a variable (namely, $\mathcal{D}_{val}$) from under the integral sign and placed it as an indexing set for the summation. What is the correct mathematical interpretation of this step?