) ▁is ▁a ▁free ▁and ▁open - source ▁vector ▁graphics ▁editor ▁application ▁designed ▁especially ▁for ▁creating ▁illustr ations ▁of ▁mathematical ▁articles . ▁ ▁V R R ▁has ▁a ▁simple ▁but ▁powerful ▁operation ▁set : ▁creating , ▁manip ulating ▁and ▁transform ing ▁basic ▁graph ic ▁primit ives , ▁which ▁are ▁points , ▁segments , ▁rational ▁Bé z ier ▁curves , ▁elli ptic ▁ar cs ▁etc . ▁All ▁objects ▁can ▁be ▁determined ▁not ▁only ▁by ▁absolute ▁coordinates , ▁but ▁also ▁by ▁geometric ▁dependencies ▁on ▁other ▁objects ▁– ▁inter sections , ▁significant ▁points , ▁other ▁curves ▁etc . ▁When ▁an ▁object ▁is ▁changed , ▁the ▁dependent ▁objects ▁are ▁re calcul ated ▁automatically . ▁This ▁enables ▁you ▁to ▁modify ▁the ▁image ▁easily ▁without ▁breaking ▁the ▁lines ▁vis ually ▁tied ▁together . ▁▁ ▁V R R ▁has ▁a ▁s oph istic ated ▁system ▁for ▁working ▁with ▁text . ▁In ▁addition ▁to ▁common ▁text ▁objects , ▁it ▁allows ▁you ▁to ▁create ▁text ▁objects ▁types et ▁by ▁Te X ▁and ▁make ▁them ▁part ▁of ▁your ▁image . ▁This ▁is ▁especially ▁useful ▁for ▁including ▁math ▁expressions ▁into ▁the ▁picture . ▁▁ ▁The ▁editor ▁is ▁able ▁to ▁import ▁from ▁and ▁export ▁to ▁files ▁in ▁common ▁data ▁formats ▁( export ▁to ▁PDF , ▁PS , ▁E PS ▁and ▁SV G , ▁import ▁from ▁I PE 5 ▁and ▁SV G ). ▁▁ ▁V R R ▁runs ▁on ▁Linux ▁and ▁uses ▁a ▁graph ical ▁user ▁interface ▁based ▁on ▁the ▁X ▁Window ▁System ▁and ▁GT K . ▁▁ ▁The ▁V R R ▁project ▁was ▁started ▁as