:: deftheorem Def5 defines VFunc EUCLID_8:def 5 :
for f1, f2, f3 being PartFunc of REAL,REAL
for b₄ being Function of REAL,(REAL 3) holds
( b₄ = VFunc (f1,f2,f3) iff for t being Real holds b₄ . t = |[(f1 . t),(f2 . t),(f3 . t)]| );