▁band ed ▁matrices ▁( available ▁for ▁band ed ▁matrices , ▁e . g . ▁in ▁L AP ACK ; ▁for ▁a ▁prototype ▁sky line ▁code , ▁see ▁). ▁▁ ▁Before ▁storing ▁a ▁matrix ▁in ▁sky line ▁format , ▁the ▁rows ▁and ▁columns ▁are ▁typically ▁ren umber ed ▁to ▁reduce ▁the ▁size ▁of ▁the ▁sky line ▁( the ▁number ▁of ▁non zero ▁entries ▁stored ) ▁and ▁to ▁decrease ▁the ▁number ▁of ▁operations ▁in ▁the ▁sky line ▁Ch oles ky ▁algorithm . ▁The ▁same ▁he ur istic ▁ren umber ing ▁algorithm ▁that ▁reduce ▁the ▁band width ▁are ▁also ▁used ▁to ▁reduce ▁the ▁sky line . ▁The ▁basic ▁and ▁one ▁of ▁the ▁earliest ▁algorithms ▁to ▁do ▁that ▁is ▁reverse ▁C uth ill – Mc K ee ▁algorithm . ▁▁ ▁However , ▁sky line ▁storage ▁is ▁not ▁as ▁popular ▁for ▁very ▁large ▁systems ▁( many ▁millions ▁of ▁equations ) ▁because ▁sky line ▁Ch oles ky ▁is ▁not ▁so ▁easily ▁adapted ▁for ▁mass ively ▁parallel ▁computing , ▁and ▁general ▁sparse ▁methods , ▁which ▁store ▁only ▁the ▁non zero ▁entries ▁of ▁the ▁matrix , ▁become ▁more ▁efficient ▁for ▁very ▁large ▁problems ▁due ▁to ▁much ▁less ▁fill - in . ▁ ▁See ▁also ▁▁ ▁S parse ▁matrix ▁Band ▁matrix ▁Front al ▁sol ver ▁ ▁References ▁▁ ▁Category : S parse ▁matrices <0x0A> </s> ▁The ▁z od iac ▁is ▁an ▁area ▁of ▁the ▁sky ▁that ▁extends ▁approximately ▁ 8 ° ▁north ▁or ▁south ▁( as ▁measured ▁in ▁cel est ial ▁latitude ) ▁of ▁the ▁e cli ptic , ▁the ▁apparent ▁path