▁it ▁is ▁en harm on ically ▁equivalent ▁to ▁the ▁perfect ▁oct ave . ▁ ▁Since ▁an ▁oct ave ▁can ▁be ▁described ▁as ▁a ▁major ▁sevent h ▁augment ed ▁by ▁a ▁di at onic ▁sem it one , ▁the ▁augment ed ▁sevent h ▁is ▁the ▁sum ▁of ▁an ▁oct ave , ▁plus ▁the ▁difference ▁between ▁the ▁chrom atic ▁and ▁di at onic ▁sem it ones , ▁which ▁makes ▁it ▁a ▁highly ▁variable ▁quantity ▁between ▁one ▁meant one ▁tun ing ▁and ▁the ▁next . ▁In ▁standard ▁equal ▁temper ament , ▁in ▁fact , ▁it ▁is ▁identical ▁to ▁the ▁perfect ▁oct ave ▁( ), ▁because ▁both ▁sem it ones ▁have ▁the ▁same ▁size . ▁In ▁ 1 9 ▁equal ▁temper ament , ▁on ▁the ▁other ▁hand , ▁the ▁interval ▁is ▁ 6 3 ▁c ents ▁short ▁of ▁an ▁oct ave , ▁i . e . ▁ 1 1 3 7 ▁c ents . ▁More ▁typical ▁meant one ▁tun ings ▁fall ▁between ▁these ▁extrem es , ▁giving ▁it ▁an ▁intermediate ▁size . ▁ ▁In ▁just ▁in ton ation , ▁three ▁major ▁third s ▁in ▁succession ▁make ▁up ▁an ▁augment ed ▁sevent h , ▁which ▁is ▁just ▁short ▁of ▁an ▁oct ave ▁by ▁ 4 1 . 0 5 ▁c ents . ▁ ▁Adding ▁a ▁dies is ▁to ▁this ▁makes ▁up ▁an ▁oct ave . ▁ ▁Hence , ▁this ▁interval ' s ▁complement , ▁the ▁dimin ished ▁second , ▁is ▁often ▁referred ▁to ▁as ▁a ▁dies is . ▁ ▁See ▁also ▁List ▁of ▁meant one ▁intervals ▁ ▁S