let V be RealLinearSpace; :: thesis: for v1, v2 being VECTOR of V
for f being Function of the carrier of V,REAL holds f (#) <*v1,v2*> = <*((f . v1) * v1),((f . v2) * v2)*>
let v1, v2 be VECTOR of V; :: thesis: for f being Function of the carrier of V,REAL holds f (#) <*v1,v2*> = <*((f . v1) * v1),((f . v2) * v2)*>
let f be Function of the carrier of V,REAL ; :: thesis: f (#) <*v1,v2*> = <*((f . v1) * v1),((f . v2) * v2)*>
A1: len (f (#) <*v1,v2*>) = len <*v1,v2*> by Def9
.= 2 by FINSEQ_1:61 ;
then A2: ( dom (f (#) <*v1,v2*>) = {1,2} & 1 in {1,2} & 2 in {1,2} ) by FINSEQ_1:4, FINSEQ_1:def 3, TARSKI:def 2;
then A3: (f (#) <*v1,v2*>) . 1 = (f . (<*v1,v2*> /. 1)) * (<*v1,v2*> /. 1) by Def9
.= (f . (<*v1,v2*> /. 1)) * v1 by FINSEQ_4:26
.= (f . v1) * v1 by FINSEQ_4:26 ;
(f (#) <*v1,v2*>) . 2 = (f . (<*v1,v2*> /. 2)) * (<*v1,v2*> /. 2) by A2, Def9
.= (f . (<*v1,v2*> /. 2)) * v2 by FINSEQ_4:26
.= (f . v2) * v2 by FINSEQ_4:26 ;
hence f (#) <*v1,v2*> = <*((f . v1) * v1),((f . v2) * v2)*> by A1, A3, FINSEQ_1:61; :: thesis: verum