INNER PRODUCT SPACE
Def Dot Product :-
For x,y € Rⁿ , the dot product of x&y,
denoted x.y is defined as
x.y=x1y1+x2y2+…..xnyn
Where x=(x1,x2,…xn) and y=(y1,y2,…yn)
Note that Dot Product of two vectors in Rⁿ is a number not a vector. Obviously,
x.x=||x||² for all x €Rⁿ. The dot product on Rⁿ has following properties:
◦ x.x ≥ 0 for all x € Rⁿ.
◦ x.x = 0 if and only if x = 0.
◦ For y € Rⁿ fixed , the map from Rⁿ to R that sends x € Rⁿ to x.y is linear.
◦ x.y = y.x for all x,y € Rⁿ.
Def INNER PRODUCT :-
An inner product on V is a fiction that takes each ordered pair (u,v) of
elements V to a number <u,v> € F and has following properties :-
◦ Positivity:
< v,u > ≥ 0 for all v € V
◦ Definiteness :
<v,v> = 0 if and only if v=0
◦ Additivity in first Slot :
< u+v,w> = <u,w> + <v,w> for all u,v,w € V
◦ Homogenity in first slot :
<^u,v> = ^ <u,v> for all ^ € F and all u,v €V
◦ Conjugate Symmetry :
<u,v>=<v,u> for all u,v € V
Properties of INNER PRODUCT :
◦ For each fixed u €V , the function that takes v to <v,u> is a linear map from V to F.
◦ <0,u> = 0 for every u € V.
◦ <u,0> = 0 for every u € V.
◦ <u,v+w> = <u,v> + <u,w> for all u,v,w € V.
◦ <u,^v> = ^<u,v> for all ^ €F and u,v € V.
Def Norm :
For v€V , the norm of v , denoted ||v|| is defined by
||v||=√<v,v>
Basic Properties :
Suppose v€V
◦ ||v|| = 0 if and only if v=0.
◦ ||^v|| = |^| ||v|| for all ^€F.