# Meaning of a symbol in a research paper

The 2014 paper "Iteration-Free Computation of Gauss--Legendre Quadrature Nodes and Weights" by I. Bogaert (https://doi.org/10.1137/140954969) contains the following expression in Appendix A:

What is the meaning of the "LL" here? It is not defined in the body of the paper and it's such a commonly occurring character sequence that Googling for it has proven futile.

• that may be just a typo. have you tried asking the author of the paper? his contact details are in the footnote on page 1. Mar 16 '18 at 14:00
• Maybe there was some \LL latex macro, but they forgot \? Mar 16 '18 at 15:09
• This is corroborated by the preprint (biblio.ugent.be/publication/5683230/file/5683237.pdf), which does not contain the LL. (I refrain from commenting on the effect of publisher copy-editing on mathematical correctness and merely remark that a general strategy for such -- and similar -- cases is to try to find a preprint and see if it the formula is clearer there: a preprint is usually updated if serious mathematical typos are found in press, but a published paper is rarely corrected unless the author takes the blame.) Mar 16 '18 at 15:17
• Just as a confirmation, another "post-pring" I found was on ResearchGate: researchgate.net/publication/… where the LL symbol does not appear. Mar 16 '18 at 21:15