Definition talk:Step Function

By implication, Larson allows:

$f\left({x}\right) = \lambda_1 \chi_{\mathbb I_1} + \lambda_2 \chi_{\mathbb I_2} + \cdots$

to be infinite, but he never gives an explicit definition that allows me to put up an "also defined as". Anyone have a source for this alternative definition, or is it just an oddity of Larson's? --GFauxPas (talk) 14:07, 21 May 2014 (UTC)

You can always put a call to Template:Expand. Such infinite sums are pretty common, but I'm unsure whether I'd call them step functions. It's justifiable I think. — Lord_Farin (talk) 20:12, 21 May 2014 (UTC)